The cosmic merger history of supermassive black hole binaries (SMBHBs) is expected to produce a low-frequency gravitational wave background (GWB). Here we investigate how signs of the discrete nature of this GWB can manifest in pulsar timing arrays through excursions from, and breaks in, the expected $f_{mathrm{GW}}^{-2/3}$ power-law of the GWB strain spectrum. To do this, we create a semi-analytic SMBHB population model, fit to NANOGrav's 15 yr GWB amplitude, and with 1,000 realizations we study the populations' characteristic strain and residual spectra. Comparing our models to the NANOGrav 15 yr spectrum, we find two interesting excursions from the power-law. The first, at $2 ; mathrm{nHz}$, is below our GWB realizations with $p$-value significance $p = 0.05$ to $0.06$ ($approx 1.8 sigma - 1.9 sigma$). The second, at $16 ; mathrm{nHz}$, is above our GWB realizations with $p = 0.04$ to $0.15$ ($approx 1.4 sigma - 2.1 sigma$). We explore the properties of a loud SMBHB which could cause such an excursion. Our simulations also show that the expected number of SMBHBs decreases by three orders of magnitude, from $sim 10^6$ to $sim 10^3$, between $2; mathrm{nHz}$ and $20 ; mathrm{nHz}$. This causes a break in the strain spectrum as the stochasticity of the background breaks down at $26^{+28}_{-19} ; mathrm{nHz}$, consistent with predictions pre-dating GWB measurements. The diminished GWB signal from SMBHBs at frequencies above the $26$~nHz break opens a window for PTAs to detect continuous GWs from individual SMBHBs or GWs from the early universe.

We present the results of a Bayesian search for gravitational wave (GW) memory in the NANOGrav 12.5 yr data set. We find no convincing evidence for any gravitational wave memory signals in this data set. We find a Bayes factor of 2.8 in favor of a model that includes a memory signal and common spatially uncorrelated red noise (CURN) compared to a model including only a CURN. However, further investigation shows that a disproportionate amount of support for the memory signal comes from three dubious pulsars. Using a more flexible red-noise model in these pulsars reduces the Bayes factor to 1.3. Having found no compelling evidence, we go on to place upper limits on the strain amplitude of GW memory events as a function of sky location and event epoch. These upper limits are computed using a signal model that assumes the existence of a common, spatially uncorrelated red noise in addition to a GW memory signal. The median strain upper limit as a function of sky position is approximately 3.3 × 10<SUP>‑14</SUP>. We also find that there are some differences in the upper limits as a function of sky position centered around PSR J0613‑0200. This suggests that this pulsar has some excess noise that can be confounded with GW memory. Finally, the upper limits as a function of burst epoch continue to improve at later epochs. This improvement is attributable to the continued growth of the pulsar timing array.

The radio galaxy 3C 66B has been hypothesized to host a supermassive black hole binary (SMBHB) at its center based on electromagnetic observations. Its apparent 1.05 yr period and low redshift (∼0.02) make it an interesting testbed to search for low-frequency gravitational waves (GWs) using pulsar timing array (PTA) experiments. This source has been subjected to multiple searches for continuous GWs from a circular SMBHB, resulting in progressively more stringent constraints on its GW amplitude and chirp mass. In this paper, we develop a pipeline for performing Bayesian targeted searches for eccentric SMBHBs in PTA data sets, and test its efficacy by applying it to simulated data sets with varying injected signal strengths. We also search for a realistic eccentric SMBHB source in 3C 66B using the NANOGrav 12.5 yr data set employing PTA signal models containing Earth term-only as well as Earth+pulsar term contributions using this pipeline. Due to limitations in our PTA signal model, we get meaningful results only when the initial eccentricity e <SUB>0</SUB> < 0.5 and the symmetric mass ratio η > 0.1. We find no evidence for an eccentric SMBHB signal in our data, and therefore place 95% upper limits on the PTA signal amplitude of 88.1 ± 3.7 ns for the Earth term-only and 81.74 ± 0.86 ns for the Earth+pulsar term searches for e <SUB>0</SUB> < 0.5 and η > 0.1. Similar 95% upper limits on the chirp mass are (1.98 ± 0.05) × 10<SUP>9 </SUP>and (1.81 ± 0.01) × 10<SUP>9</SUP> M <SUB>☉</SUB>. These upper limits, while less stringent than those calculated from a circular binary search in the NANOGrav 12.5 yr data set, are consistent with the SMBHB model of 3C 66B developed from electromagnetic observations.

Recently we found compelling evidence for a gravitational-wave background with Hellings and Downs (HD) correlations in our 15 yr data set. These correlations describe gravitational waves as predicted by general relativity, which has two transverse polarization modes. However, more general metric theories of gravity can have additional polarization modes, which produce different interpulsar correlations. In this work, we search the NANOGrav 15 yr data set for evidence of a gravitational-wave background with quadrupolar HD and scalar-transverse (ST) correlations. We find that HD correlations are the best fit to the data and no significant evidence in favor of ST correlations. While Bayes factors show strong evidence for a correlated signal, the data does not strongly prefer either correlation signature, with Bayes factors ∼2 when comparing HD to ST correlations, and ∼1 for HD plus ST correlations to HD correlations alone. However, when modeled alongside HD correlations, the amplitude and spectral index posteriors for ST correlations are uninformative, with the HD process accounting for the vast majority of the total signal. Using the optimal statistic, a frequentist technique that focuses on the pulsar-pair cross-correlations, we find median signal-to-noise ratios of 5.0 for HD and 4.6 for ST correlations when fit for separately, and median signal-to-noise ratios of 3.5 for HD and 3.0 for ST correlations when fit for simultaneously. While the signal-to-noise ratios for each of the correlations are comparable, the estimated amplitude and spectral index for HD are a significantly better fit to the total signal, in agreement with our Bayesian analysis.

We investigate how the properties of massive black hole binaries influence the observed properties of core galaxies. We compare the observed trend in stellar mass deficit as a function of total stellar mass in the core galaxy with predicted trends in IllustrisTNG. We calculate mass deficits in simulated galaxies by applying subgrid, post-processing physics based on the results of literature N-body experiments. We find that the median value of the posterior distribution for the minimum binary mass ratio capable of creating a core is 0.7. For the gas mass fraction above which a core is erased, we find a median value of 0.6. Thus, low mass ratio binaries do not contribute to core formation and gas-rich mergers must lead to star formation within the nucleus, ultimately erasing the core. Such constraints have important implications for the overall massive black hole binary population, black hole-galaxy co-evolution, and the origin of the gravitational wave background.

We investigate the time-varying electromagnetic emission of a low-mass-ratio supermassive black hole binary (SMBHB) embedded in a circumprimary disc, with a particular interest in variability of shocks driven by the binary. We perform a 2D, locally isothermal hydrodynamics simulation of an SMBHB with mass ratio q = 0.01 and separation a = 100 R<SUB>g</SUB>, using a physically self-consistent steady disc model. We estimate the electromagnetic variability from the system by monitoring accretion on to the secondary and using an artificial viscosity scheme to capture shocks and monitor the energy dissipated. The SMBHB produces a wide, eccentric gap in the disc, previously only observed for larger mass ratios, which we attribute to our disc model being much thinner (H/R ≈ 0.01 near the secondary) than is typical of previous works. The eccentric gap drives periodic accretion on to the secondary SMBH on a time-scale matching the orbital period of the binary, $t_{rm {bin}}approx 0.1,,rm {yr}$, implying that the variable accretion regime of the SMBHB parameter space extends to lower mass ratios than previously established. Shocks driven by the binary are periodic, with a period matching the orbital period, and the shocks are correlated with the accretion rate, with peaks in the shock luminosity lagging peaks in the accretion rate by 0.43 t<SUB>bin</SUB>. We propose that the correlation of these quantities represents a useful identifier of SMBHB candidates, via observations of correlated variability in X-ray and ultraviolet monitoring of active galactic nuclei, rather than single-waveband periodicity alone.

We present an analysis searching for dual AGN among 62 high-redshift ($2.5 < z < 3.5$) X-ray sources selected from publicly available deep Chandra fields. We aim to quantify the frequency of dual AGN in the high-redshift Universe, which holds implications for black hole merger timescales and low-frequency gravitational wave detection rates. We analyze each X-ray source using BAYMAX, an analysis tool that calculates the Bayes factor for whether a given archival Chandra AGN is more likely a single or dual point source. We find no strong evidence for dual AGN in any individual source in our sample. We then increase our sensitivity to search for dual AGN across the sample by comparing our measured distribution of Bayes factors to that expected from a sample composed entirely of single point sources, and again find no evidence for dual AGN in the observed sample distribution. Although our analysis utilizes one of the largest Chandra catalogs of high-$z$ X-ray point sources available to study, the findings remain limited by the modest number of sources observed at the highest spatial resolution with Chandra and the typical count rates of the detected sources. Our non-detection allows us to place an upper-limit on the X-ray dual AGN fraction between $2.5<z<3.5$ of 4.8%. Expanding substantially on these results at X-ray wavelengths will require future surveys spanning larger sky areas and extending to fainter fluxes than has been possible with Chandra. We illustrate the potential of the AXIS mission concept in this regard.

Analyses of pulsar timing data have provided evidence for a stochastic gravitational wave background in the nanohertz frequency band. The most plausible source of this background is the superposition of signals from millions of supermassive black hole binaries. The standard statistical techniques used to search for this background and assess its significance make several simplifying assumptions, namely (i) Gaussianity, (ii) isotropy, and most often, (iii) a power-law spectrum. However, a stochastic background from a finite collection of binaries does not exactly satisfy any of these assumptions. To understand the effect of these assumptions, we test standard analysis techniques on a large collection of realistic simulated data sets. The data-set length, observing schedule, and noise levels were chosen to emulate the NANOGrav 15 yr data set. Simulated signals from millions of binaries drawn from models based on the Illustris cosmological hydrodynamical simulation were added to the data. We find that the standard statistical methods perform remarkably well on these simulated data sets, even though their fundamental assumptions are not strictly met. They are able to achieve a confident detection of the background. However, even for a fixed set of astrophysical parameters, different realizations of the universe result in a large variance in the significance and recovered parameters of the background. We also find that the presence of loud individual binaries can bias the spectral recovery of the background if we do not account for them.

We present 0.″22-resolution Atacama Large Millimeter/submillimeter Array (ALMA) observations of CO(2-1) emission from the circumnuclear gas disk in the red nugget relic galaxy PGC 11179. The disk shows regular rotation, with projected velocities near the center of 400 km s<SUP>-1</SUP>. We assume the CO emission originates from a dynamically cold, thin disk and fit gas-dynamical models directly to the ALMA data. In addition, we explore systematic uncertainties by testing the impacts of various model assumptions on our results. The supermassive black hole (BH) mass (M <SUB>BH</SUB>) is measured to be M <SUB>BH</SUB> = (1.91 ± 0.04 [1σ statistical] ${}_{-0.51}^{+0.11}$ [systematic]) × 10<SUP>9</SUP> M <SUB>⊙</SUB>, and the H-band stellar mass-to-light ratio M/L <SUB> H </SUB> = 1.620 ± 0.004 [1σ statistical] ${}_{-0.107}^{+0.211}$ [systematic] M <SUB>⊙</SUB>/L <SUB>⊙</SUB>. This M <SUB>BH</SUB> is consistent with the BH mass-stellar velocity dispersion relation but over-massive compared to the BH mass-bulge luminosity relation by a factor of 3.7. PGC 11179 is part of a sample of local compact early-type galaxies that are plausible relics of z ~ 2 red nuggets, and its behavior relative to the scaling relations echoes that of three relic galaxy BHs previously measured with stellar dynamics. These over-massive BHs could suggest that BHs gain most of their mass before their host galaxies do. However, our results could also be explained by greater intrinsic scatter at the high-mass end of the scaling relations, or by systematic differences in gas- and stellar-dynamical methods. Additional M <SUB>BH</SUB> measurements in the sample, including independent cross-checks between molecular gas- and stellar-dynamical methods, will advance our understanding of the co-evolution of BHs and their host galaxies.

Context. Stellar dynamic-based black hole mass measurements of M 87 are twice that determined via ionized gas kinematics; the former are closer to the mass estimated from the diameter of the gravitationally lensed ring around the black hole. <BR /> Aims: Using a deeper and more comprehensive ionized gas kinematic data set, we aim to better constrain the complex morphology and kinematics of the nuclear ionized gas and thus gain insights into the reasons behind the disagreement between the mass measurements. <BR /> Methods: We use new narrow field mode with adaptive optics and wide field mode integral field spectroscopic data from the Multi Unit Spectroscopic Explorer instrument on the Very Large Telescope to model the morphology and kinematics of multiple ionized gas emission lines (primarily Hα+[N II] λλ6548,6583 and [O I] λ6300) in the nucleus of M 87. We used Kinemetry to fit the position angle, inclination, and velocities of the subarcsecond ionized gas disk. We used KinMSpy to create simulated datacubes across a range of black hole masses and disk inclinations, and parameterized the differences of the resulting residual (observed minus simulated) velocity maps, in order to obtain the best-fit model. <BR /> Results: The new deep data set reveals complexities in the nuclear ionized gas kinematics that were not seen in earlier sparse and shallower Hubble Space Telescope spectroscopy. Several ionized gas filaments, some with high flow velocities, can be traced down into the projected sphere of influence. However, not all truly pass close to the black hole. Additionally, we find evidence of a partially filled biconical outflow, aligned with the jet, with radial velocities of up to 400 km s<SUP>−1</SUP>. The subarcsecond rotating ionized gas "disk" is well resolved in our datacubes. The velocity isophotes of this disk are twisted, and the position angle of the innermost gas disk (≲5 pc) tends toward a value perpendicular to the radio jet axis. The complexity of the nuclear morphology and kinematics (the mix of a warped disk with spiral arms, large linewidths, strong outflows, and filaments crossing the black hole in projection) precludes the measurement of an accurate black hole mass from the ionized gas kinematics. Two results, each relatively weak but together more convincing, support a high-mass black hole (∼6.0 × 10<SUP>9</SUP> M<SUB>⊙</SUB>) in a low-inclination disk (i ∼ 25°) rather than a low-mass black hole (∼3.5 × 10<SUP>9</SUP> M<SUB>⊙</SUB>) in a i = 42° disk: (a) Kinemetry fits to the subarcsecond disk support inclinations of ∼20°-25° rather than 42°; and (b) velocity residual (observed minus simulated) maps with slightly smaller residuals are found for the former case. The specific (sub-Keplerian) radiatively inefficient accretion flow (RIAF) model previously proposed to reconcile the mass measurement discrepancy was also tested: the sub-Keplerian factor used in this model is not sufficiently small to make a high-mass black hole in a RIAF inflow masquerade as a low-mass black hole in a Keplerian inflow. In general, Keplerian disk models perform significantly better than the RIAF model when fitting the subarcsecond ionized gas disk. <BR /> Conclusions: A disk inclination close to 25° for the nuclear gas disk (rather than the previously posited 42°) and the warp in the subarcsecond ionized gas disk help reconcile the contradictory nature of key earlier results: (a) the mass discrepancy between stellar and ionized gas black hole masses (our results support the former) and (b) the misorientation between the axes of the ionized gas disk and the jet (we find them to be aligned in both two and three dimensions). Furthermore, we identify a previously unknown 400 km s<SUP>−1</SUP> (partially filled) biconical outflow along the (three-dimensional) jet axis and show that the velocities of the two largest ionized gas filaments at 8″-30″ nuclear distances can be explained primarily by rotation in the extension of the nuclear ionized gas disk (inclination ∼25°).

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has reported evidence for the presence of an isotropic nanohertz gravitational-wave background (GWB) in its 15 yr data set. However, if the GWB is produced by a population of inspiraling supermassive black hole binary (SMBHB) systems, then the background is predicted to be anisotropic, depending on the distribution of these systems in the local Universe and the statistical properties of the SMBHB population. In this work, we search for anisotropy in the GWB using multiple methods and bases to describe the distribution of the GWB power on the sky. We do not find significant evidence of anisotropy. By modeling the angular power distribution as a sum over spherical harmonics (where the coefficients are not bound to always generate positive power everywhere), we find that the Bayesian 95% upper limit on the level of dipole anisotropy is (C <SUB> l=1</SUB>/C <SUB> l=0</SUB>) < 27%. This is similar to the upper limit derived under the constraint of positive power everywhere, indicating that the dipole may be close to the data-informed regime. By contrast, the constraints on anisotropy at higher spherical-harmonic multipoles are strongly prior dominated. We also derive conservative estimates on the anisotropy expected from a random distribution of SMBHB systems using astrophysical simulations conditioned on the isotropic GWB inferred in the 15 yr data set and show that this data set has sufficient sensitivity to probe a large fraction of the predicted level of anisotropy. We end by highlighting the opportunities and challenges in searching for anisotropy in pulsar timing array data.

The Australian, Chinese, European, Indian, and North American pulsar timing array (PTA) collaborations recently reported, at varying levels, evidence for the presence of a nanohertz gravitational wave background (GWB). Given that each PTA made different choices in modeling their data, we perform a comparison of the GWB and individual pulsar noise parameters across the results reported from the PTAs that constitute the International Pulsar Timing Array (IPTA). We show that despite making different modeling choices, there is no significant difference in the GWB parameters that are measured by the different PTAs, agreeing within $1sigma$. The pulsar noise parameters are also consistent between different PTAs for the majority of the pulsars included in these analyses. We bridge the differences in modeling choices by adopting a standardized noise model for all pulsars and PTAs, finding that under this model there is a reduction in the tension in the pulsar noise parameters. As part of this reanalysis, we "extended" each PTA's data set by adding extra pulsars that were not timed by that PTA. Under these extensions, we find better constraints on the GWB amplitude and a higher signal-to-noise ratio for the Hellings and Downs correlations. These extensions serve as a prelude to the benefits offered by a full combination of data across all pulsars in the IPTA, i.e., the IPTA's Data Release 3, which will involve not just adding in additional pulsars, but also including data from all three PTAs where any given pulsar is timed by more than as single PTA.

We examine the effect of supermassive black hole (SMBH) mass scaling relation choice on the inferred SMBH mass population since redshift z ~ 3. To make robust predictions for the gravitational wave background (GWB), we must have a solid understanding of the underlying SMBH demographics. Using the SDSS and 3D-HST + CANDELS surveys for 0 < z < 3, we evaluate the inferred SMBH masses from two SMBH-galaxy scaling relations: M<SUB>BH</SUB>-M<SUB>bulge</SUB> and M<SUB>BH</SUB>-σ. Our SMBH mass functions come directly from stellar mass measurements for M<SUB>BH</SUB>-M<SUB>bulge</SUB>, and indirectly from stellar mass and galaxy radius measurements along with the galaxy mass fundamental plane for M<SUB>BH</SUB>-σ. We find that there is a substantial difference in predictions especially for z > 1, and this difference increases out to z = 3. In particular, we find that using velocity dispersion predicts a greater number of SMBHs with masses greater than 10<SUP>9</SUP> M<SUB>⊙</SUB>. The GWB that pulsar timing arrays find evidence for is higher in amplitude than expected from GWB predictions which rely on high-redshift extrapolations of local SMBH mass-galaxy scaling relations. The difference in SMBH demographics resulting from different scaling relations may be the origin for the mismatch between the signal amplitude and predictions. Generally, our results suggest that a deeper understanding of the potential redshift evolution of these relations is needed if we are to draw significant insight from their predictions at z > 1.

The NANOGrav 15 yr data set shows evidence for the presence of a low-frequency gravitational-wave background (GWB). While many physical processes can source such low-frequency gravitational waves, here we analyze the signal as coming from a population of supermassive black hole (SMBH) binaries distributed throughout the Universe. We show that astrophysically motivated models of SMBH binary populations are able to reproduce both the amplitude and shape of the observed low-frequency gravitational-wave spectrum. While multiple model variations are able to reproduce the GWB spectrum at our current measurement precision, our results highlight the importance of accurately modeling binary evolution for producing realistic GWB spectra. Additionally, while reasonable parameters are able to reproduce the 15 yr observations, the implied GWB amplitude necessitates either a large number of parameters to be at the edges of expected values or a small number of parameters to be notably different from standard expectations. While we are not yet able to definitively establish the origin of the inferred GWB signal, the consistency of the signal with astrophysical expectations offers a tantalizing prospect for confirming that SMBH binaries are able to form, reach subparsec separations, and eventually coalesce. As the significance grows over time, higher-order features of the GWB spectrum will definitively determine the nature of the GWB and allow for novel constraints on SMBH populations.

We present the first results from the Revealing Low-Luminosity Active Galactic Nuclei (ReveaLLAGN) survey, a JWST survey of seven nearby LLAGN. We focus on two observations with the Mid-Infrared Instrument's (MIRI) Medium Resolution Spectrograph (MRS) of the nuclei of NGC 1052 and Sombrero (NGC 4594 / M104). We also compare these data to public JWST data of a higher-luminosity AGN, NGC 7319 and NGC 7469. JWST clearly separates the AGN spectrum from the galaxy light even in Sombrero, the faintest target in our survey; the AGN components have very red spectra. We find that the emission-line widths in both NGC 1052 and Sombrero increase with increasing ionization potential, with FWHM > 1000 km/s for lines with ionization potential > 50 eV. These lines are also significantly blue-shifted in both LLAGN. The high ionization potential lines in NGC 7319 show neither broad widths or significant blue shifts. Many of the lower ionization potential emission lines in Sombrero show significant blue wings extending > 1000 km/s. These features and the emission-line maps in both galaxies are consistent with outflows along the jet direction. Sombrero has the lowest luminosity high-ionization potential lines ([Ne V] and [O IV]) ever measured in the mid-IR, but the relative strengths of these lines are consistent with higher luminosity AGN. On the other hand, the [Ne V] emission is much weaker relative to the [Ne III] and [Ne II] lines of higher-luminosity AGN. These initial results show the great promise that JWST holds for identifying and studying the physical nature of LLAGN.

We present the results of a Bayesian search for gravitational wave (GW) memory in the NANOGrav 12.5-yr data set. We find no convincing evidence for any gravitational wave memory signals in this data set (Bayes factor = 2.8). As such, we go on to place upper limits on the strain amplitude of GW memory events as a function of sky location and event epoch. These upper limits are computed using a signal model that assumes the existence of a common, spatially uncorrelated red noise in addition to a GW memory signal. The median strain upper limit as a function of sky position is approximately $3.3 times 10^{-14}$. We also find that there are some differences in the upper limits as a function of sky position centered around PSR J0613$-$0200. This suggests that this pulsar has some excess noise which can be confounded with GW memory. Finally, the upper limits as a function of burst epoch continue to improve at later epochs. This improvement is attributable to the continued growth of the pulsar timing array.

The 15 yr pulsar timing data set collected by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) shows positive evidence for the presence of a low-frequency gravitational-wave (GW) background. In this paper, we investigate potential cosmological interpretations of this signal, specifically cosmic inflation, scalar-induced GWs, first-order phase transitions, cosmic strings, and domain walls. We find that, with the exception of stable cosmic strings of field theory origin, all these models can reproduce the observed signal. When compared to the standard interpretation in terms of inspiraling supermassive black hole binaries (SMBHBs), many cosmological models seem to provide a better fit resulting in Bayes factors in the range from 10 to 100. However, these results strongly depend on modeling assumptions about the cosmic SMBHB population and, at this stage, should not be regarded as evidence for new physics. Furthermore, we identify excluded parameter regions where the predicted GW signal from cosmological sources significantly exceeds the NANOGrav signal. These parameter constraints are independent of the origin of the NANOGrav signal and illustrate how pulsar timing data provide a new way to constrain the parameter space of these models. Finally, we search for deterministic signals produced by models of ultralight dark matter (ULDM) and dark matter substructures in the Milky Way. We find no evidence for either of these signals and thus report updated constraints on these models. In the case of ULDM, these constraints outperform torsion balance and atomic clock constraints for ULDM coupled to electrons, muons, or gluons.

Evidence for a low-frequency stochastic gravitational-wave background has recently been reported based on analyses of pulsar timing array data. The most likely source of such a background is a population of supermassive black hole binaries, the loudest of which may be individually detected in these data sets. Here we present the search for individual supermassive black hole binaries in the NANOGrav 15 yr data set. We introduce several new techniques, which enhance the efficiency and modeling accuracy of the analysis. The search uncovered weak evidence for two candidate signals, one with a gravitational-wave frequency of ~4 nHz, and another at ~170 nHz. The significance of the low-frequency candidate was greatly diminished when Hellings-Downs correlations were included in the background model. The high-frequency candidate was discounted due to the lack of a plausible host galaxy, the unlikely astrophysical prior odds of finding such a source, and since most of its support comes from a single pulsar with a commensurate binary period. Finding no compelling evidence for signals from individual binary systems, we place upper limits on the strain amplitude of gravitational waves emitted by such systems. At our most sensitive frequency of 6 nHz, we place a sky-averaged 95% upper limit of 8 × 10<SUP>-15</SUP> on the strain amplitude. We also calculate an exclusion volume and a corresponding effective radius, within which we can rule out the presence of black hole binaries emitting at a given frequency.

Pulsar timing arrays (PTAs) are galactic-scale gravitational wave (GW) detectors. Each individual arm, composed of a millisecond pulsar, a radio telescope, and a kiloparsecs-long path, differs in its properties but, in aggregate, can be used to extract low-frequency GW signals. We present a noise and sensitivity analysis to accompany the NANOGrav 15 yr data release and associated papers, along with an in-depth introduction to PTA noise models. As a first step in our analysis, we characterize each individual pulsar data set with three types of white-noise parameters and two red-noise parameters. These parameters, along with the timing model and, particularly, a piecewise-constant model for the time-variable dispersion measure, determine the sensitivity curve over the low-frequency GW band we are searching. We tabulate information for all of the pulsars in this data release and present some representative sensitivity curves. We then combine the individual pulsar sensitivities using a signal-to-noise ratio statistic to calculate the global sensitivity of the PTA to a stochastic background of GWs, obtaining a minimum noise characteristic strain of 7 × 10<SUP>-15</SUP> at 5 nHz. A power-law-integrated analysis shows rough agreement with the amplitudes recovered in NANOGrav's 15 yr GW background analysis. While our phenomenological noise model does not model all known physical effects explicitly, it provides an accurate characterization of the noise in the data while preserving sensitivity to multiple classes of GW signals.

Pulsar timing array collaborations, such as the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), are seeking to detect nanohertz gravitational waves emitted by supermassive black hole binaries formed in the aftermath of galaxy mergers. We have searched for continuous waves from individual circular supermassive black hole binaries using NANOGrav's recent 12.5 yr data set. We created new methods to accurately model the uncertainties on pulsar distances in our analysis, and we implemented new techniques to account for a common red-noise process in pulsar timing array data sets while searching for deterministic gravitational wave signals, including continuous waves. As we found no evidence for continuous waves in our data, we placed 95% upper limits on the strain amplitude of continuous waves emitted by these sources. At our most sensitive frequency of 7.65 nHz, we placed a sky-averaged limit of h <SUB>0</SUB> < (6.82 ± 0.35) × 10<SUP>-15</SUP>, and h <SUB>0</SUB> < (2.66 ± 0.15) × 10<SUP>-15</SUP> in our most sensitive sky location. Finally, we placed a multimessenger limit of ${ mathcal M } (1.41pm 0.02)times {10}^{9},{M}_{odot }$ on the chirp mass of the supermassive black hole binary candidate 3C 66B.

We report multiple lines of evidence for a stochastic signal that is correlated among 67 pulsars from the 15 yr pulsar timing data set collected by the North American Nanohertz Observatory for Gravitational Waves. The correlations follow the Hellings-Downs pattern expected for a stochastic gravitational-wave background. The presence of such a gravitational-wave background with a power-law spectrum is favored over a model with only independent pulsar noises with a Bayes factor in excess of 10<SUP>14</SUP>, and this same model is favored over an uncorrelated common power-law spectrum model with Bayes factors of 200-1000, depending on spectral modeling choices. We have built a statistical background distribution for the latter Bayes factors using a method that removes interpulsar correlations from our data set, finding p = 10<SUP>-3</SUP> (≈3σ) for the observed Bayes factors in the null no-correlation scenario. A frequentist test statistic built directly as a weighted sum of interpulsar correlations yields p = 5 × 10<SUP>-5</SUP> to 1.9 × 10<SUP>-4</SUP> (≈3.5σ-4σ). Assuming a fiducial f <SUP>-2/3</SUP> characteristic strain spectrum, as appropriate for an ensemble of binary supermassive black hole inspirals, the strain amplitude is ${2.4}_{-0.6}^{+0.7}times {10}^{-15}$ (median + 90% credible interval) at a reference frequency of 1 yr<SUP>-1</SUP>. The inferred gravitational-wave background amplitude and spectrum are consistent with astrophysical expectations for a signal from a population of supermassive black hole binaries, although more exotic cosmological and astrophysical sources cannot be excluded. The observation of Hellings-Downs correlations points to the gravitational-wave origin of this signal.

We present observations and timing analyses of 68 millisecond pulsars (MSPs) comprising the 15 yr data set of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). NANOGrav is a pulsar timing array (PTA) experiment that is sensitive to low-frequency gravitational waves (GWs). This is NANOGrav's fifth public data release, including both "narrowband" and "wideband" time-of-arrival (TOA) measurements and corresponding pulsar timing models. We have added 21 MSPs and extended our timing baselines by 3 yr, now spanning nearly 16 yr for some of our sources. The data were collected using the Arecibo Observatory, the Green Bank Telescope, and the Very Large Array between frequencies of 327 MHz and 3 GHz, with most sources observed approximately monthly. A number of notable methodological and procedural changes were made compared to our previous data sets. These improve the overall quality of the TOA data set and are part of the transition to new pulsar timing and PTA analysis software packages. For the first time, our data products are accompanied by a full suite of software to reproduce data reduction, analysis, and results. Our timing models include a variety of newly detected astrometric and binary pulsar parameters, including several significant improvements to pulsar mass constraints. We find that the time series of 23 pulsars contain detectable levels of red noise, 10 of which are new measurements. In this data set, we find evidence for a stochastic GW background.

The International Pulsar Timing Array 2nd data release is the combination of data sets from worldwide collaborations. In this study, we search for continuous waves: gravitational wave signals produced by individual supermassive black hole binaries in the local universe. We consider binaries on circular orbits and neglect the evolution of orbital frequency over the observational span. We find no evidence for such signals and set sky averaged 95 per cent upper limits on their amplitude h<SUB>95</SUB>. The most sensitive frequency is 10 nHz with h<SUB>95</SUB> = 9.1 × 10<SUP>-15</SUP>. We achieved the best upper limit to date at low and high frequencies of the PTA band thanks to improved effective cadence of observations. In our analysis, we have taken into account the recently discovered common red noise process, which has an impact at low frequencies. We also find that the peculiar noise features present in some pulsars data must be taken into account to reduce the false alarm. We show that using custom noise models is essential in searching for continuous gravitational wave signals and setting the upper limit.

This paper presents rigorous tests of pulsar timing array methods and software, examining their consistency across a wide range of injected parameters and signal strength. We discuss updates to the 15-year isotropic gravitational-wave background analyses and their corresponding code representations. Descriptions of the internal structure of the flagship algorithms texttt{Enterprise} and texttt{PTMCMCSampler} are given to facilitate understanding of the PTA likelihood structure, how models are built, and what methods are currently used in sampling the high-dimensional PTA parameter space. We introduce a novel version of the PTA likelihood that uses a two-step marginalization procedure that performs much faster when the white noise parameters remain fixed. We perform stringent tests of consistency and correctness of the Bayesian and frequentist analysis software. For the Bayesian analysis, we test prior recovery, injection recovery, and Bayes factors. For the frequentist analysis, we test that the cross-correlation-based optimal statistic, when modified to account for a non-negligible gravitational-wave background, accurately recovers the amplitude of the background. We also summarize recent advances and tests performed on the optimal statistic in the literature from both GWB detection and parameter estimation perspectives. The tests presented here validate current and future analyses of PTA data.

Since a black hole does not emit light from its interior, nor does it have a surface on which light from nearby sources can be reflected, observational study of black hole physics requires observing the gravitational impact of the black hole on its surroundings. A massive black hole leaves a dynamical imprint on stars and gas close by. Gas in the immediate vicinity of an accreting massive black hole can, due to the presence of the black hole, shine so brightly that it outshines the light of the billions of stars in its host galaxy and be detected across the Universe. By observing the emission from stars and gas and determining their kinematics scientists can extract vital information not only on the fundamental properties of the black holes themselves but also the impact they have on their surroundings. As it turns out, supermassive black holes appear to play a vital role in shaping the Universe as we know it, as they can profoundly impact the star formation history in galaxies. As a consequence, these black holes indirectly impact the cosmic build up of chemical elements heavier than Helium and thus affect when and where life can form. For these reasons alone, observations of massive black holes constitute a very active research area of modern astrophysics. In this chapter we aim to provide a general overview -- fit for a non-expert -- of what scientists have learned, and hope to learn, from analyzing observations of massive black holes and the material around them.

Since a black hole does not emit light from its interior or does it have a surface on which light from nearby sources can be reflected, observational study of black hole physics requires observing the gravitational impact of the black hole on its surroundings. A massive black hole leaves a dynamical imprint on stars and gas close by. Gas in the immediate vicinity of an accreting massive black hole can, due to the presence of the black hole, shine so brightly that it outshines the light of the billions of stars in its host galaxy and be detected across the Universe. By observing the emission from stars and gas and determining their kinematics, scientists can extract vital information not only on the fundamental properties of the black holes themselves but also on the impact they have on their surroundings. As it turns out, supermassive black holes appear to play a vital role in shaping the Universe as we know it, as they can profoundly impact the star formation history in galaxies. As a consequence, these black holes indirectly impact the cosmic build up of chemical elements heavier than helium and thus affect when and where life can form. For these reasons alone, observations of massive black holes constitute a very active research area of modern astrophysics. In this chapter, we aim to provide a general overview — fit for a non-expert — of what scientists have learned, and hope to learn, from analyzing observations of massive black holes and the material around them. We deliberately do not provide a review of the vast literature on this topic but refer to relevant sample journal articles or reviews, when available, for readers interested in exploring the topics in greater detail.

We present new 5 GHz Very Large Array observations of a sample of eight active intermediate-mass black holes with masses 10<SUP>4.9</SUP> M<SUB>⊙</SUB> < M < 10<SUP>6.1</SUP> M<SUB>⊙</SUB> found in galaxies with stellar masses M<SUB>*</SUB> < 3 × 10<SUP>9</SUP> M<SUB>⊙</SUB>. We detected five of the eight sources at high significance. Of the detections, four were consistent with a point source, and one (SDSS J095418.15+471725.1, with black hole mass M < 10<SUP>5</SUP> M<SUB>⊙</SUB>) clearly shows extended emission that has a jet morphology. Combining our new radio data with the black hole masses and literature X-ray measurements, we put the sources on the Fundamental Plane of black hole accretion. We find that the extent to which the sources agree with the Fundamental Plane depends on their star-forming/composite/active galactic nucleus (AGN) classification based on optical narrow emission-line ratios. The single star-forming source is inconsistent with the Fundamental Plane. The three composite sources are consistent, and three of the four AGN sources are inconsistent with the Fundamental Plane. We argue that this inconsistency is genuine and not a result of misattributing star formation to black hole activity. Instead, we identify the sources in our sample that have AGN-like optical emission-line ratios as not following the Fundamental Plane and thus caution the use of the Fundamental Plane to estimate masses without additional constraints, such as radio spectral index, radiative efficiency, or the Eddington fraction.

HARMONI is the first light, adaptive optics assisted, integral field spectrograph for the European Southern Observatory's Extremely Large Telescope (ELT). A work-horse instrument, it provides the ELT's diffraction limited spectroscopic capability across the near-infrared wavelength range. HARMONI will exploit the ELT's unique combination of exquisite spatial resolution and enormous collecting area, enabling transformational science. The design of the instrument is being finalized, and the plans for assembly, integration and testing are being detailed. We present an overview of the instrument's capabilities from a user perspective, and provide a summary of the instrument's design. We also include recent changes to the project, both technical and programmatic, that have resulted from red-flag actions. Finally, we outline some of the simulated HARMONI observations currently being analyzed.

We have used Hubble Space Telescope (HST) images, SAURON Integral Field Spectroscopy (IFS), and adaptative optics assisted Gemini NIFS near-infrared K-band IFS to map the stellar and gas distribution, excitation and kinematics of the inner few kpc of the nearby edge-on S0 galaxy NGC 4111. The HST images map its ≈450 pc diameter dusty polar ring, with an estimated gas mass ≥10<SUP>7</SUP> M<SUB>⊙</SUB>. The NIFS data cube maps the inner 110 pc radius at ≈7 pc spatial resolution, revealing a ≈220 pc diameter polar ring in hot (2267 ± 166 K) molecular H<SUB>2</SUB> 1-0 S(1) gas embedded in the polar ring. The stellar velocity field shows disc-dominated kinematics along the galaxy plane both in the SAURON large scale and in the NIFS nuclear-scale data. The large-scale [O III] λ5007 Å velocity field shows a superposition of two disc kinematics: one similar to that of the stars and another along the polar ring, showing non-circular motions that seem to connect with the velocity field of the nuclear H<SUB>2</SUB> ring, whose kinematics indicate accelerated inflow to the nucleus. The estimated mass inflow rate is enough not only to feed an active galactic nucleus (AGN) but also to trigger circumnuclear star formation in the near future. We propose a scenario in which gas from the polar ring, which probably originated from the capture of a dwarf galaxy, is moving inwards and triggering an AGN, as supported by the local X-ray emission, which seems to be the source of the H<SUB>2</SUB> 1-0 S(1) excitation. The fact that we see neither near-UV nor Br γ emission suggests that the nascent AGN is still deeply buried under the optically thick dust of the polar ring.

We present results of a multiwavelength analysis of SDSS J025214.67-002813.7, a system that has been previously classified as a binary active galactic nucleus (AGN) candidate based on periodic signals detected in the optical light curves. We use available radio-X-ray observations of the system to investigate the true accretion nature. Analyzing new observations from XMM-Newton and NuSTAR, we characterize the X-ray emission and search for evidence of circumbinary accretion. Although the 0.5-10 keV spectrum shows evidence of an additional soft emission component, possibly due to extended emission from hot nuclear gas, we find the spectral shape is consistent with that of a single AGN. Compiling a full multiwavelength spectral energy distribution (SED), we also search for signs of circumbinary accretion, such as a "notch" in the continuum due to the presence of minidisks. We find that the radio-optical emission agrees with the SED of a standard, radio-quiet, AGN; however, there is a large deficit in emission blueward of ~1400 Å. Although this deficit in emission can plausibly be attributed to a binary AGN system, we find that the SED of SDSS J0252-0028 is better explained by emission from a reddened, single AGN. However, future studies of the expected hard X-ray emission associated with binary AGNs (especially in the unequal-mass regime) will allow for more rigorous analyses of the binary AGN hypothesis.

We present the results of a high-cadence spectroscopic and imaging monitoring campaign of the active galactic nucleus (AGN) of NGC 4395. High signal-to-noise-ratio spectra were obtained at the Gemini-N 8 m telescope using the GMOS integral field spectrograph (IFS) on 2019 March 7 and at the Keck I 10 m telescope using the Low-Resolution Imaging Spectrometer with slit masks on 2019 March 3 and April 2. Photometric data were obtained with a number of 1 m-class telescopes during the same nights. The narrow-line region (NLR) is spatially resolved; therefore, its variable contributions to the slit spectra make the standard procedure of relative flux calibration impractical. We demonstrate that spatially resolved data from the IFS can be effectively used to correct the slit-mask spectral light curves. While we obtained no reliable lag owing to the lack of a strong variability pattern in the light curves, we constrain the broad-line time lag to be less than 3 hr, consistent with the photometric lag of ~80 minutes reported by Woo et al. By exploiting the high-quality spectra, we measure the second moment of the broad component of the Hα emission line to be 586 ± 19 km s<SUP>-1</SUP>, superseding the lower value reported by Woo et al. Combining the revised line dispersion and the photometric time lag, we update the black hole mass to (1.7 ± 0.3) × 10<SUP>4</SUP> M<SUB>⊙</SUB>.

We present 0"14 resolution Atacama Large Millimeter/submillimeter Array (ALMA) CO(2-1) observations of the circumnuclear gas disk in UGC 2698, a local compact galaxy. The disk exhibits regular rotation with projected velocities rising to 450 km s<SUP>-1</SUP> near the galaxy center. We fit gas-dynamical models to the ALMA data cube, assuming the CO emission originates from a dynamically cold, thin disk, and measured the mass of the supermassive black hole (BH) in UGC 2698 to be M<SUB>BH</SUB> = (2.46 ± 0.07 [1σ statistical] ${}_{-0.78}^{+0.70}$ [systematic]) × 10<SUP>9</SUP> M<SUB>⊙</SUB>. UGC 2698 is part of a sample of nearby early-type galaxies that are plausible z ~ 2 red nugget relics. Previous stellar-dynamical modeling for three galaxies in the sample found BH masses consistent with the BH mass-stellar velocity dispersion (M<SUB>BH</SUB> - σ<SUB>⋆</SUB>) relation but over-massive relative to the BH mass-bulge luminosity (M<SUB>BH</SUB> - L<SUB>bul</SUB>) correlation, suggesting that BHs may gain the majority of their mass before their host galaxies. However, UGC 2698 is consistent with both M<SUB>BH</SUB> - σ<SUB>⋆</SUB> and M<SUB>BH</SUB> - L<SUB>bul</SUB>. As UGC 2698 has the largest stellar mass and effective radius in the local compact galaxy sample, it may have undergone more recent mergers that brought it in line with the BH scaling relations. Alternatively, given that the three previously measured compact galaxies are outliers from M<SUB>BH</SUB> - L<SUB>bul</SUB>, while UGC 2698 is not, there may be significant scatter at the poorly sampled high-mass end of the relation. Additional gas-dynamical M<SUB>BH</SUB> measurements for the compact galaxy sample will improve our understanding of BH-galaxy co-evolution.

The accretion mechanism and SED of black holes at low luminosities are critical questions regarding BHs, but they are still poorly understood. We propose for Chandra data of 22 LLAGN, that combined with existing archival data on 9, will yield a complete data set of all 31 galaxies in the Gemini/NIFS AO LLP black-hole mass campaign. These data will enable massive science: 1. Create the best LLAGN SEDs by virtue of the amount and quality of the data available for a sample with a broad range of black hole masses and Eddington ratios. 2. Specifically study the L_X-L_NIR relation, which is critical for understanding LLAGN and for making the most use of upcoming JWST data. 3. Add value to the Gemini LLP black-hole mass campaign by measuring BH accretion when Gemini find BH mass upper limits.

Feedback from active galactic nuclei (AGN) has proven to be a critical ingredient in the current picture of galaxy assembly and growth. However, observational constraints on AGN-driven outflows face technical challenges and as a result, the cold molecular gas outflow properties of type-1 AGN are not well known. We present new IRAM NOrthern Extended Millimeter Array observations of CO$, (1{-}0)$ in F07599+6508, Z11598 - 0112, F13342 + 3932, and PG1440 + 356, all nearby type-1 AGN and ultraluminous infrared galaxies. We achieve spatial resolution of 1-3 arcsec corresponding to physical scales of 2-8 kpc and spectral resolution of 15-60 km s<SUP>-1</SUP>, which enables updated CO$, (1{-}0)$ redshifts and a detailed morphological view of the cold molecular gas in these sources. The CO$, (1{-}0)$ luminosities, $L_{CO}^{prime }$, are in the range 2-12 × 10<SUP>9</SUP> K km s<SUP>-1</SUP> pc<SUP>2</SUP> and inferred molecular gas masses, M(H<SUB>2</SUB>), are in the range 2-9 × 10<SUP>9</SUP> M<SUB>⊙</SUB>. The velocity fields and gas distributions do not unambiguously identify any of these sources as having outflows. However, Z11598 - 0112 has signs of infalling material and after the subtraction of a rotating disc model PG 1440 + 356 shows complex kinematics in the residuals that may indicate an outflow or warped disc.

JWST will be the most sensitive tool ever built for studying the accretion onto supermassive black holes (SMBHs) at the centers of galaxies. While quasars and bright active galactic nuclei (AGN) provide spectacular examples of this accretion, a vast majority of galaxies have black holes accreting at much lower rates. Although these low luminosity AGN (LLAGN) are not as well studied or understood as their brighter counterparts, it is clear their inner structures differ significantly from the accretion disks in luminous AGN. JWST spectroscopy provides a unique opportunity to significantly advance our understanding of LLAGN. Our proposal focuses on getting IFU spectra from 1.7 to 28 microns for seven of the nearest LLAGN spanning four orders of magnitude in both black hole mass and accretion rate (these will also be complemented by two GTO targets). JWST's spatial resolution will enable easy separation of the AGN from the host galaxy light providing us with spectral templates of low luminosity AGN spectra in the infrared for the first time. Detailed physical modeling of both the line emission and spectral energy distributions of these LLAGN spectra will reveal the physical structure of low luminosity AGN, and how it varies with the mass and accretion rate of the SMBH. We will also use these spectral templates to empirically determine the most sensitive lines and SED features for spectroscopically and photometrically identifying LLAGN in more distant galaxies where the AGN won't be spatially resolved. ReveaLLAGN will both significantly enhance our understanding of AGN and open a new window for future AGN studies with JWST.

We present results from our X-ray analysis of a systematic search for triple active galactic nuclei (AGNs) in nearby (z < 0.077) triple galaxy mergers. We analyze archival Chandra observations of seven triple galaxy mergers with BAYMAX (Bayesian Analysis of Multiple AGNs in X-rays), fitting each observation with single, dual, and triple X-ray point-source models. In doing so, we conclude that one triple merger has one X-ray point source (SDSS J0858+1822, although it is unlikely to be an AGN), five triple mergers are likely composed of two X-ray point sources (NGC 3341, SDSS J1027+1749, SDSS J1631+2352, SDSS J1708+2153, and SDSS J2356-1016), and one system is composed of three X-ray point sources (SDSS J0849+1114). By fitting the individual X-ray spectra of each point source, we analyze the 2-7 keV luminosities, as well as the levels of obscuration associated with each potential AGN. We find that 4/5 dual X-ray point-source systems have primary and secondary point sources with bright X-ray luminosities (L<SUB>2-7kev</SUB> > 10<SUP>40</SUP> erg s<SUP>-1</SUP>), possibly associated with four new undetected dual AGNs. The dual and triple-point-source systems are found to have physical separations between 3 and 9 kpc and flux ratios between 2 × 10<SUP>-3</SUP> and 0.84. A multiwavelength analysis to determine the origin of the X-ray point sources discovered in this work is presented in our companion paper (Foord et al. 2020c).

We present results from a multiwavelength analysis searching for multiple active galactic nucleus (AGN) systems in nearby (z < 0.077) triple galaxy mergers. Combining archival Chandra, Sloan Digital Data Survey (SDSS), Wide-field Infrared Survey Explorer (WISE), and Very Large Array observations, we quantify the rate of nearby triple AGNs, as well as investigate possible connections between supermassive black hole accretion and merger environments. Analyzing the multiwavelength observations of seven triple galaxy mergers, we find that one triple merger has a single AGN (NGC 3341); we discover, for the first time, four likely dual AGNs (SDSS J1027+1749, SDSS J1631+2352, SDSS J1708+2153, and SDSS J2356-1016); we confirm one triple-AGN system, SDSS J0849+1114; and one triple merger in our sample remains ambiguous (SDSS J0858+1822). Analyzing the WISE data, we find a trend of increasing N<SUB>H</SUB> (associated with the primary AGN) as a function of increasing W1 - W2 color, reflecting that the motions of gas and dust are coupled in merging environments, where large amounts of both can be funneled into the active central region during mergers. Additionally, we find that the one triple-AGN system in our sample has the highest levels of N<SUB>H</SUB> and W1 - W2 color, while the dual-AGN candidates all have lower levels; these results are consistent with theoretical merger simulations that suggest that higher levels of nuclear gas are more likely to activate AGNs in mergers.

Supermassive black holes (BHs) play a key role in galaxy evolution. One fundamental open question is whether BHs and galaxies grow in lockstep, or if the growth of one precedes that of the other. We have uncovered a sample of compact galaxies that are thought to be local analogs of z~2 quiescent galaxies. These local (z ≤ 0.02) systems have uniformly old (≥10 Gyr) stellar populations and small sizes (effective radii of 0.7-3.1 kpc) for their stellar masses [(0.5-3.8)×10<SUP>11</SUP> solar masses]. Previous stellar-dynamical modeling of several of these galaxies found over-massive BHs relative to the BH mass - bulge luminosity relation, suggesting that perhaps BHs build the majority of their mass before their host galaxies. Here, we present 0.20"-resolution Atacama Large Millimeter/submillimeter Array (ALMA) CO(2-1) observations of the rotating circumnuclear disk in the local compact galaxy UGC 2698. We fit gas-dynamical models directly to the ALMA data cube, assuming the CO emission originates from a dynamically cold, thin disk, and we use the dynamic nested sampling code dynesty to determine Bayesian posteriors. We find a black hole mass in UGC 2698 of 2.46×10<SUP>9</SUP> solar masses, with an error budget dominated by an estimated systematic uncertainty of ~30%. We discuss our results and locate UGC 2698 relative to the BH - host galaxy relationships, finding it is consistent with the local scaling relations. Expanding the sample of local compact galaxies with dynamical BH mass measurements will pave the way for a deeper understanding of BH - galaxy co-evolution.

We use Chandra X-ray observations to look for evidence of a recoiling black hole from the brightest cluster galaxy in Abell 2261 (A2261-BCG). A2261-BCG is a strong candidate for a recoiling black hole because of its large, flat stellar core, revealed by Hubble Space Telescope imaging observations. We took 100 ks observations with Chandra and combined it with 35 ks of archival observations to look for low-level accretion onto a black hole of expected mass $Msim {10}^{10},{M}_{odot }$ that could possibly be located in one of four off-center stellar knots near the galaxy's center or else in the optical center of the galaxy or in the location of radio emission. We found no X-ray emission arising from a point source in excess of the cluster gas and can place limits on the accretion of any black hole in the central region to a 2-7 keV flux below $4.3times {10}^{-16} mathrm{erg} {{rm{s}}}^{-1} {mathrm{cm}}^{-2}$ , corresponding to a bolometric Eddington fraction of about 10<SUP>-6</SUP>. Thus there is either no 10<SUP>10</SUP> ${M}_{odot }$ black hole in the core of A2261-BCG, or it is accreting at a low level. We also discuss the morphology of the X-ray emitting gas in the cluster and how its asymmetry is consistent with a large dynamic event.

HARMONI is the adaptive optics assisted, near-infrared and visible light integral field spectrograph for the Extremely Large Telescope (ELT). A first light instrument, it provides the work-horse spectroscopic capability for the ELT. As the project approaches its Final Design Review milestone, the design of the instrument is being finalized, and the plans for assembly, integration and testing are being detailed. We present an overview of the instrument's capabilities from a user perspective, provide a summary of the instrument's design, including plans for operations and calibrations, and provide a brief glimpse of the predicted performance for a specific observing scenario. The paper also provides some details of the consortium composition and its evolution since the project commenced in 2015.

The NASA LISA Study Team was tasked to study how NASA might support US scientists to participate and maximize the science return from the Laser Interferometer Space Antenna (LISA) mission. LISA is gravitational wave observatory led by ESA with NASA as a junior partner, and is scheduled to launch in 2034. Among our findings: LISA science productivity is greatly enhanced by a full-featured US science center and an open access data model. As other major missions have demonstrated, a science center acts as both a locus and an amplifier of research innovation, data analysis, user support, user training and user interaction. In its most basic function, a US Science Center could facilitate entry into LISA science by hosting a Data Processing Center and a portal for the US community to access LISA data products. However, an enhanced LISA Science Center could: support one of the parallel independent processing pipelines required for data product validation; stimulate the high level of research on data analysis that LISA demands; support users unfamiliar with a novel observatory; facilitate astrophysics and fundamental research; provide an interface into the subtleties of the instrument to validate extraordinary discoveries; train new users; and expand the research community through guest investigator, postdoc and student programs. Establishing a US LISA Science Center well before launch can have a beneficial impact on the participation of the broader astronomical community by providing training, hosting topical workshops, disseminating mock catalogs, software pipelines, and documentation. Past experience indicates that successful science centers are established several years before launch; this early adoption model may be especially relevant for a pioneering mission like LISA.

Using a month-long X-ray light curve from RXTE/PCA and 1.5 month-long UV continuum light curves from IUE spectra in 1220-1970 Å, we performed a detailed time-lag study of the Seyfert 1 galaxy NGC 7469. Our cross-correlation analysis confirms previous results showing that the X-rays are delayed relative to the UV continuum at 1315 Šby 3.49 ± 0.22 d, which is possibly caused by either propagating fluctuation or variable Comptonization. However, if variations slower than 5 d are removed from the X-ray light curve, the UV variations then lag behind the X-ray variations by 0.37 ± 0.14 d, consistent with reprocessing of the X-rays by a surrounding accretion disc. A very similar reverberation delay is observed between Swift/XRT X-ray and Swift/UVOT UVW2, U light curves. Continuum light curves extracted from the Swift/GRISM spectra show delays with respect to X-rays consistent with reverberation. Separating the UV continuum variations faster and slower than 5 d, the slow variations at 1825 Šlag those at 1315 Šby 0.29 ± 0.06 d, while the fast variations are coincident (0.04 ± 0.12 d). The UV/optical continuum reverberation lag from IUE, Swift, and other optical telescopes at different wavelengths are consistent with the relationship: τ ∝ λ<SUP>4/3</SUP>, predicted for the standard accretion disc theory while the best-fitting X-ray delay from RXTE and Swift/XRT shows a negative X-ray offset of ∼0.38 d from the standard disc delay prediction.

We present an analysis of 12 optically selected dual active galactic nucleus (AGN) candidates at z < 0.34. Each candidate was originally identified via double-peaked [O III] λ5007 emission lines and received follow-up Chandra and Hubble Space Telescope (HST) observations. Because the X-ray data are low-count (<100 counts) with small separations (<1″), a robust analysis is necessary for classifying each source. Pairing long-slit [O III] observations with existing Chandra observations, we re-analyze the X-ray observations with Bayesian AnalYsis of AGNs in X-rays to determine whether the X-ray emission from each system is more likely a single or dual point source. We find that 4 of the 12 sources are likely dual X-ray point-source systems. We examine each point source's spectra via a Monte Carlo method that probabilistically identifies the likely origin of each photon. When doing so, we find that (I) the secondary X-ray point sources in two of the systems have L<SUB>X</SUB> < 10<SUP>40</SUP> erg s<SUP>-1</SUP>, such that we cannot rule out a non-AGN origin, (II) one source has a secondary with L<SUB>X</SUB> > 10<SUP>40</SUP> erg s<SUP>-1</SUP> but a spectrum that is too soft to definitively preclude being X-ray emitting diffuse gas that was photoionized by the primary AGN, and (III) one system (SDSS J1126+2944) is a dual AGN. Additionally, using complementary HST observations, we analyze a subsample of systems that are visually identified as merging. Our results suggest that dual AGNs may preferentially reside in mergers with small separations, consistent with both simulations and observations.

We present black hole (BH) mass estimates for two nearby elliptical galaxies using ionized gas disk kinematics. These are particularly important cases since both galaxies contain stellar kinematics estimates of their black hole mass. For NGC 4552, the existing estimates (~5x10<SUP>8</SUP> solar masses) from stellar kinematics are insecure. We perform our own Schwarzschild modeling of SAURON and STIS spectra to obtain M<SUB>BH</SUB> = 6X10<SUP>8</SUP> solar masses, which still has large uncertainties. The gas in NGC 4552 exhibits orderly rotation that is well-fit by a gas disk model (despite the imperfect dust disk), providing a much better constraint on the BH mass. For NGC 4697, a secure black hole mass exists from stellar kinematics based on STIS calcium triplet spectroscopy. This disky elliptical sports a large, well-organized dust disk and, again, the rotation can be fit well by a gas disk model. The gas disk models are able to constrain the M/L as well and find close agreement with the stellar kinematics value. In both cases, the BH mass from gas kinematics is smaller than the stellar kinematics value without attributing the line broadening to asymmetric drift.

Modern observational techniques and technologies are insufficient for identifying sub-parsec separation supermassive black hole (SMBH) binaries, despite their paramount importance to the evolution of SMBHs and the galaxies which host them. Current methods focus on resolving spectral signatures such as distinct broad line regions or multiple HI absorption lines in jets, but these are still unable to probe the extremely close separations relevant to gravitational wave explorations. In this work, we focus on the potential for time-domain identification of sub-parsec SMBH binaries. We use a 2D hydrodynamics simulation of a close-separation (100 AU), low mass-ratio (q = 0.01) SMBH binary to explore the characteristic frequencies with which optical, UV, and X-ray emissions will vary in these sources. We find strong variability across the electromagnetic spectrum with periods corresponding to the binary orbital time. In the X-rays, there is additional strong variability at integer multiples of the orbital frequency, with even multiples of the orbital frequency exhibiting doublet peaks in the Fourier power spectrum. There is also a significant enhancement of the continuum X-ray emission over a single SMBH model due to shocks excited along the accretion streams of the secondary's accretion disk and where they strike the primary's accretion disk and the circumbinary disk. These features can enable the identification of SMBH binary candidates through both single-epoch observations and long-term time monitoring.

In the coming decade we will have the capability to dynamically detect 1000 to hundred thousand solar mass black holes should they exit. This white paper describes how measuring the mass function of the elusive intermediate-mass black holes will provide unique insight into the formation of the first massive black holes.

In the coming decade, 30-m class telescopes will allow us to make dynamical mass measurements of the largest black holes (1) in the local universe, which is critical for understanding the black hole mass function, and (2) out to z 1.5, which is critical for black hole growth and charting the coevolution (or not) of black holes and galaxies.

We present the first results from Bayesian AnalYsis of Multiple AGN in X-rays (BAYMAX), a tool that uses a Bayesian framework to quantitatively evaluate whether a given Chandra observation is more likely a single or dual point source. Although the most robust method of determining the presence of dual active galactic nuclei (AGNs) is to use X-ray observations, only sources that are widely separated relative to the instrument's point-spread function are easy to identify. It becomes increasingly difficult to distinguish dual AGNs from single AGNs when the separation is on the order of Chandra's angular resolution (<1″). Using likelihood models for single and dual point sources, BAYMAX quantitatively evaluates the likelihood of an AGN for a given source. Specifically, we present results from BAYMAX analyzing the lowest-mass dual AGN candidate to date, SDSS J0914+0853, where archival Chandra data shows a possible secondary AGN ∼ 0.″3 from the primary. Analyzing a new 50 ks Chandra observation, results from BAYMAX shows that SDSS J0914+0853 is most likely a single AGN with a Bayes factor of 13.5 in favor of a single point source model. Further, posterior distributions from the dual point source model are consistent with emission from a single AGN. We find a very low probability of SDSS J0914+0853 being a dual AGN system with a flux ratio f > 0.3 and separation r > 0.″3. Overall, BAYMAX will be an important tool for correctly classifying candidate dual AGNs in the literature, as well as studying the dual AGN population where past spatial resolution limits have prevented systematic analyses.

Galaxy mergers are predicted to represent a significant stage of SMBH growth. This white paper discusses the key questions in galaxy mergers, dual, and offset AGN, and proposes solutions using future high-resolution multiwavelength observatories in the X-rays (AXIS, Lynx), NIR and MIR (JWST and 30-meter class telescopes), and submillimeter (ALMA).

Supermassive black holes are located at the center of most, if not all, massive galaxies. They follow close correlations with global properties of their host galaxies (scaling relations), and are thought to play a crucial role in galaxy evolution. Yet, we lack a complete understanding of fundamental aspects of their growth across cosmic time. In particular, we still do not understand: (1) whether black holes or their host galaxies grow faster and (2) what is the maximum mass that black holes can reach. The high angular resolution capability and sensitivity of 30-m class telescopes will revolutionize our understanding of the extreme end of the black hole and galaxy mass scale. With such facilities, we will be able to dynamically measure masses of the largest black holes and characterize galaxy properties out to redshift $z sim 1.5$. Together with the evolution of black hole-galaxy scaling relations since $z sim 1.5$, the maximum mass black hole will shed light on the main channels of black hole growth.

We have examined a sample of 13 sub-Eddington supermassive black holes hosted by galaxies spanning a variety of morphological classifications to further understand the empirical fundamental plane of black hole activity. This plane describes black holes from stellar-mass to supermassive and relates the mass of an accreting black hole and its radio and X-ray luminosities. A key factor in studying the fundamental plane is the turnover frequency, i.e., the frequency at which the radio continuum emission becomes optically thin. We measured this turnover frequency using new Very Large Array observations combined, when necessary, with archival Chandra observations. Radio observations are in the range of 5-40 GHz across four frequency bands in B configuration, giving high spatial resolution to focus on the core emission. We use Markov chain Monte Carlo methods to fit the continuum emission in order to find the turnover frequency. After testing for correlations, the turnover frequency does not display a significant dependence on either the mass or mass accretion rate, indicating that more complicated physics than simple scaling and optical depth effects are at play, as has been suggested by recent theoretical work.

Modern observational techniques and technologies are insufficient for identifying sub-parsec separation supermassive black hole (SMBH) binaries, despite their paramount importance to the evolution of SMBHs and the galaxies which host them. Current methods focus on identifying multiple absorption lines in AGN jets or spectrally distinct Broad Line Regions, but these are still unable to probe the extremely close separations relevant to gravitational wave explorations. In this talk, we focus on the potential for time-domain identification of sub-parsec SMBH binaries. We use hydrodynamics simulations of a close-separation, low mass-ratio (q << 1) SMBH binary to explore the characteristic frequencies with which optical, UV, and X-ray emissions will vary in these sources. This talk will detail the methods employed in these simulations and their analysis and will present preliminary results demonstrating proof-of-concept for time-domain SMBH binary identification.

We present BAYMAX (Bayesian AnalYsis of Multiple AGN in X-rays), a tool that uses a Bayesian framework to quantitatively evaluate whether a given Chandra observation is a more likely a single or dual point source. Although the most robust method of determining the presence of dual AGNs is to use X-ray observations, only sources that are widely separated relative to the instrument PSF are easy to identify. It becomes increasingly difficult to distinguish dual AGNs from single AGNs when the separation is on the order of Chandra’s angular resolution (<1”), as we primarily rely on visual interpretation to determine their nature. Using likelihood models for single and dual point sources, BAYMAX is able to quantitatively evaluate the likelihood of a dual AGN for a given source via a Bayesian analysis. Specifically, we present results from BAYMAX analyzing the lowest-mass dual AGN candidate to date, SDSS J091449.05, where archival Chandra data shows a possible secondary AGN 0.3” from the primary. Analyzing a new 50 ks Chandra observation, results from BAYMAX show that SDSS J091449.05 is most likely a single-AGN based on detailed comparisons of our models to the data. Further, posterior distributions from the dual point source model are consistent with emission from a single AGN. Overall, BAYMAX will be an important tool for correctly classifying candidate dual AGNs in the literature, and, for first time, study the dual AGN population where past spatial resolution limits have prevented systematic analyses.

We have compelling evidence for stellar-mass black holes (BHs) of ~5-80 M_sun that form through the death of massive stars. We also have compelling evidence for so-called supermassive BHs (10^5-10^10 M_sun) that are predominantly found in the centers of galaxies. We have very good reason to believe there must be BHs with masses in the gap between these ranges: the first ~10^9 M_sun BHs are observed only hundreds of millions of years after the Big Bang, and all theoretically viable paths to making supermassive BHs require a stage of "intermediate" mass. However, no BHs have yet been reliably detected in the 100-10}^5 M_sun mass range. Uncovering these intermediate-mass BHs of 10^3-10^5 M_sun is within reach in the coming decade. In this white paper we highlight the crucial role that 30-m class telescopes will play in dynamically detecting intermediate-mass black holes, should they exist.

Feedback driven by active galactic nuclei (AGN) is a potentially important ingredient in the coupled growth of supermassive black holes and their host galaxies. However, how ubiquitously or to what degree the large amounts of energy and momentum that are produced by AGNs can actually couple to the surrounding interstellar medium of the host galaxy is poorly constrained observationally. In particular, examples of spatially resolved quasar-mode feedback in Type 1 AGN remain scarce. With this motivation, we have undertaken a multi-wavelength observing program to study the multiphase outflows of nearby (z~0.1) Type 1 quasars. As the nearest unobscured supermassive black holes that approach the accretion rates seen in AGN at the epochs of peak accretion activity at high redshift, these are prime laboratories for studying quasar-mode feedback in galaxies. Targets for this survey are all Type-1 quasars selected from a parent sample of nearby ultraluminous infrared galaxies and Palomar-Green quasars. We have begun observations with the NOrthern Extended Millimeter Array (NOEMA) to resolve molecular outflows in CO and with Magellan and Gemini to trace outflows of ionized gas using integral field spectroscopy. Here we present initial results from this ongoing effort, particularly highlighting the power and importance of multi-wavelength datasets to characterize outflow properties in these systems.

We present an analysis of the fundamental plane of black hole accretion, an empirical correlation of the mass of a black hole (M), its 5 GHz radio continuum luminosity (νL <SUB> ν </SUB>), and its 2-10 keV X-ray power-law continuum luminosity (L <SUB> X </SUB>). We compile a sample of black holes with primary, direct black hole-mass measurements that also have sensitive, high-spatial-resolution radio and X-ray data. Taking into account a number of systematic sources of uncertainty and their correlations with the measurements, we use Markov chain Monte Carlo methods to fit a mass-predictor function of the form {log}(M/{10}<SUP>8</SUP> {M}<SUB>⊙ </SUB>)={μ }<SUB>0</SUB>+{ξ }<SUB>μ R</SUB> {log}({L}<SUB>R</SUB>/{10}<SUP>38</SUP> {erg} {{{s}}}<SUP>-1</SUP>) + {ξ }<SUB>μ X</SUB>{log}({L}<SUB>X</SUB>/{10}<SUP>40</SUP> {erg} {{{s}}}<SUP>-1</SUP>). Our best-fit results are μ <SUB>0</SUB> = 0.55 ± 0.22, ξ <SUB> μR </SUB> = 1.09 ± 0.10, and {ξ }<SUB>μ X</SUB>=-{0.59}<SUB>-0.15</SUB><SUP>+0.16</SUP> with the natural logarithm of the Gaussian intrinsic scatter in the log-mass direction {ln}{ɛ }<SUB>μ </SUB>=-{0.04}<SUB>-0.13</SUB><SUP>+0.14</SUP>. This result is a significant improvement over our earlier mass scaling result because of the increase in active galactic nuclei sample size (from 18 to 30), improvement in our X-ray binary sample selection, better identification of Seyferts, and improvements in our analysis that takes into account systematic uncertainties and correlated uncertainties. Because of these significant improvements, we are able to consider potential influences on our sample by including all sources with compact radio and X-ray emission but ultimately conclude that the fundamental plane can empirically describe all such sources. We end with advice for how to use this as a tool for estimating black hole masses.

Radio jets play an important role in quasar feedback, but direct observations showing how the jets interact with the multi-phase interstellar medium of galaxy disks are few and far between. In this work, we provide new millimeter interferometric observations of PG 1700+518 in order to investigate the effect of its radio jet on the surrounding molecular gas. PG 1700 is a radio-quiet, low-ionization broad absorption line quasar whose host galaxy has a nearby interacting companion. On subkiloparsec scales, the ionized gas is driven to high velocities by a compact radio jet that is identified by radio interferometry. We present observations from the NOrthern Extended Millimeter Array (NOEMA) interferometer with a 3.″8 (16 kpc) synthesized beam where we detect the {CO}(1to 0) emission line at 30σ significance with a total flux of 3.12 ± 0.02 Jy km s<SUP>-1</SUP> and a typical velocity dispersion of 125 ± 5 km s<SUP>-1</SUP>. Despite the outflow in ionized gas, we find no concrete evidence that the CO gas is being affected by the radio jet on size scales of a kiloparsec or more. However, a ∼1″ drift in the spatial centroid of the CO emission as a function of velocity across the emission line and the compact nature of the jet hint that higher spatial resolution observations may reveal a signal of interaction between the jet and molecular gas.

We have examined a sample of 15 sub-Eddington supermassive black holes (SMBHs) in a variety of galaxy classifications to further understand the proposed fundamental plane of black hole activity and scaling relations between black hole masses and their radio and X-ray luminosities. This plane describes black holes from stellar-mass to supermassive. The physics probed by these sub-Eddington systems is thought to be a radiatively inefficient, jet-dominated accretion flow. By studying black holes in this regime, we can learn important information on the disk-jet connection for accreting black holes.A key factor in studying the fundamental plane is the turnover frequency — the frequency at which emission transitions from optically thick at lower frequencies to optically thin at higher frequencies. This turnover point can be measured by observing the source in both radio and X-ray. Our project aims to test the dependence of the turnover frequency on mass and mass accretion rate.Radio observations of the sample were obtained using the Karl G. Jansky Very Large Array (VLA) in the range of 5-40 GHz across four different frequency bands in A configuration to give the highest spatial resolution to focus on the core emission. Our carefully chosen sample of SMBHs with dynamically measured masses consists of two sub-samples: those with approximately constant mass accretion rate (L<SUB>X</SUB>/L<SUB>Edd </SUB>~ 10<SUP>-7</SUP>) and those with approximately constant mass (M<SUB>BH</SUB> ~ 10<SUP>8 </SUP>M<SUB>sun</SUB>). X-ray data were obtained from archival Chandra observations. To find the turnover frequency, we used Markov Chain Monte Carlo methods to fit two power laws to the radio data and the archival X-ray data. The intersection of the radio and X-ray fits is the turnover frequency.We present the results for both subsamples of SMBHs and their relationship between the turnover frequency and X-ray luminosity, which we take to scale with mass accretion rate, and jet power derived from both radio and X-ray properties.

We present an analysis of the first Chandra observation of PSO J334.2028+01.4075 (PSO J334), targeted as a binary-AGN candidate based on periodic variations of the optical flux. With no prior targeted X-ray coverage for PSO J334, our new 40 ks Chandra observation allows for the opportunity to differentiate between a single- or binary-AGN system, and if a binary, can characterize the mode of accretion. Simulations show that the two expected accretion disk morphologies for binary-AGN systems are (i) a “cavity,” where the inner region of the accretion disk is mostly empty and emission is truncated blueward of the wavelength associated with the temperature of the innermost ring, or (ii) “minidisks,” where there is substantial accretion from the circumbinary disk onto one or both of the members of the binary, each with their own shock-heated thin-disk accretion system. We find the X-ray emission to be well-fit with an absorbed power law, which is incompatible with the simple cavity scenario. Furthermore, we construct an SED of PSO J334 by combining radio through X-ray observations and find that the SED agrees well with that of a normal AGN, which is most likely incompatible with the minidisk scenario. Other analyses, such as those locating the quasar on IR color-color diagrams and analyzing the quasar mass predicted by the fundamental plane of black hole activity, further highlight the similarity of PSO J334 with respect to normal AGNs. On the multi-wavelength fronts we investigated, we find no evidence supporting PSO J334 as a binary-AGN system, though our analysis remains insensitive to some binary configurations.

We present VLA images and HST/STIS spectra of sources within the center of the brightest cluster galaxy (BCG) in Abell 2261. These observations were obtained to test the hypothesis that its extremely large, flat core reflects the ejection of its supermassive black hole. Spectra of three of the four most luminous “knots” embedded in the core were taken to test whether one may represent stars bound to a displaced massive black hole. The three knots have radial velocity offsets (| {{Δ }}V| ≲ 150 {km} {{{s}}}<SUP>-1</SUP>) from the BCG. Knots 2 and 3 show kinematics, colors, and stellar masses consistent with infalling low-mass galaxies or larger stripped cluster members. Large errors in the stellar velocity dispersion of Knot 1, however, mean that we cannot rule out the hypothesis that it hosts a high-mass black hole. A2261-BCG has a compact, relic radio source offset by 6.5 kpc (projected) from the optical core’s center, but no active radio core that would pinpoint the galaxy’s central black hole to a tight 10 GHz flux limit < 3.6 μ {Jy}. Its spectrum and morphology are suggestive of an active galactic nucleus that switched off > 48 {Myr} ago, with an equipartition condition magnetic field of 15 μG. These observations are still consistent with the hypothesis that the nuclear black hole has been ejected from its core, but the critical task of locating the supermassive black hole or demonstrating that A2261-BCG lacks one remains to be done.

The prevalence and properties of kiloparsec-scale outflows in nearby Type 1 quasars have been the subject of little previous attention. This work presents Gemini integral field spectroscopy of 10 Type 1 radio-quiet quasars at z< 0.3. The excellent image quality, coupled with a new technique to remove the point-spread function using spectral information, allows the fitting of the underlying host on a spaxel-by-spaxel basis. Fits to stars, line-emitting gas, and interstellar absorption show that 100% of the sample hosts warm ionized and/or cool neutral outflows with spatially averaged velocities (< {v}<SUB>98 % </SUB>> equiv < v+2σ > ) of 200-1300 {km} {{{s}}}<SUP>-1</SUP> and peak velocities (maximum {v}<SUB>98 % </SUB>) of 500-2600 {km} {{{s}}}<SUP>-1</SUP>. These minor-axis outflows are powered primarily by the central active galactic nucleus, reach scales of 3-12 kpc, and often fill the field of view. Including molecular data and Type 2 quasar measurements, nearby quasars show a wide range in mass outflow rates ({dM}/{dt}=1 to > 1000 {M}<SUB>⊙ </SUB> {{yr}}<SUP>-1</SUP>) and momentum boosts [(c {dp}/{dt})/{L}<SUB>{AGN</SUB>}=0.01{--}20]. After extending the mass scale to Seyferts, dM/dt and dE/dt correlate with black hole mass ({dM}/{dt}∼ {M}<SUB>{BH</SUB>}<SUP>0.7+/- 0.3</SUP> and {dE}/{dt}∼ {M}<SUB>{BH</SUB>}<SUP>1.3+/- 0.5</SUP>). Thus, the most massive black holes in the local universe power the most massive and energetic quasar-mode winds.

We propose a 100 ksec observation of the core of BCG 2261 to test for the presence of a recoiling SMBH. Binary SMBHs are thought to scour out cores in the host galaxy before coalescence of the black holes, which can lead to large recoils. Despite the importance of the connection between binary BHs, strong gravity, and galaxy evolution, it has never been conclusively observed. Without confirmation, we don't know if binary SMBHs can create stellar cores achieve high recoil velocities. We can produce the first direct observational proof of a recoiling SMBH in BCG 2261, the strongest candidate to date to host a recoiling SMBH and an extreme stellar core. With a detection, we will finally have definitive observational evidence connecting core formation, gravitational waves, and binary BHs.

We obtained a Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) F160W image of Mrk 1216. The WFC3/IR observations were executed under program GO-13050. <P />We also observed Mrk 1216 with the Near-Infrared Integral Field Spectrometer (NIFS) aided by the ALTitude conjugate Adaptive optics for the InfraRed system (ALTAIR) on Gemini North. The observations were taken on 2013 December 21 under program GN-2013A-Q-1. The observations were acquired with the H+K filter and the K grating centered on 2.2um. <P />(1 data file).

We present analysis of new Chandra data of PSO J334.2028+01.4075 (PSO J334 hereafter), a strong binary AGN candidate discovered by Liu et al. (2015) based on periodic variation of the optical flux. Recent radio coverage presented in Mooley et al. (2017) further supports that PSO J334 is a binary black hole system, as the quasar was found to be lobe-dominated with a twisted radio structure, possibly due to a precessing jet. With no prior X-ray coverage for PSO J334, our new 50 ksec Chandra observation allows for the unique opportunity to differentiate between a single or binary-AGN system, and if a binary, can characterize the mode of accretion. The two most basic sets of predictions via simulations of circum-binary accretion model are a “cavity”, where the inner region of the accretion disk is mostly empty and emission is truncated blueward of the wavelength associated with the temperature of the innermost ring, or “minidisks”, where there is substantial accretion onto one or both of the members of the binary, each with their own shock-heated thin-disk accretion system. We find the X-ray emission to be well-fit with a heavily absorbed power-law, incompatible with the cavity scenario. Further, we construct an SED of PSO J334 by combining radio through X-ray observations and compare it to standard QSO SEDs. We discuss the implications of the comparison between the SED of PSO J334 and that of a single AGN, and assess the likelihood of the binary model for PSO J334.

Dedicated photometric and spectroscopic surveys have provided unambiguous evidence for a strong stellar mass-size evolution of galaxies within the last 10 Gyr. The likely progenitors of today's most massive galaxies are remarkably small, discy, passive and have already assembled much of their stellar mass at redshift z = 2. An in-depth analysis of these objects, however, is currently not feasible due to the lack of high-quality, spatially resolved photometric and spectroscopic data. In this paper, we present a sample of nearby compact elliptical galaxies (CEGs), which bear resemblance to the massive and quiescent galaxy population at earlier times. Hubble Space Telescope (HST) and wide-field integral field unit (IFU) data have been obtained, and are used to constrain orbit-based dynamical models and stellar population synthesis (SPS) fits, to unravel their structural and dynamical properties. We first show that our galaxies are outliers in the present-day stellar mass-size relation. They are, however, consistent with the mass-size relation of compact, massive and quiescent galaxies at redshift z = 2. The compact sizes of our nearby galaxies imply high central stellar mass surface densities, which are also in agreement with the massive galaxy population at higher redshift, hinting at strong dissipational processes during their formation. Corroborating evidence for a largely passive evolution within the last 10 Gyr is provided by their orbital distribution as well as their stellar populations, which are difficult to reconcile with a very active (major) merging history. This all supports that we can use nearby CEGs as local analogues of the high-redshift, massive and quiescent galaxy population, thus providing additional constraints for models of galaxy formation and evolution.

Motivated by theoretical expectations that nuclear star clusters (NSCs) in galactic centers may provide a favorable environment for supermassive black holes to form and/or efficiently grow, we set out to measure the fraction of nearby nucleated galaxies that also host an active galactic nucleus. We targeted a distance-limited sample of 98 objects with the Chandra X-ray Telescope, down to a uniform X-ray luminosity threshold of ∼10<SUP>38</SUP> erg s<SUP>-1</SUP>. The sample is composed of 47 late-types and 51 early-types, enabling us to further investigate the active fraction as a function of galactic morphology. After correcting for contamination to the nuclear X-ray signal from bright X-ray binaries, we measure an active fraction f=11.2{ % }<SUB>-4.9</SUB><SUP>+7.4</SUP> (1σ C.L.) across the whole sample, in agreement with previous estimates based on a heterogeneous combination of optical, X-ray, and radio diagnostics, by Seth et al. After accounting for the different stellar mass distributions in our samples, we find no statistically significant difference in the active fraction of early- versus late-type nucleated galaxies, with f=10.6{ % }<SUB>-4.9</SUB><SUP>+11.9</SUP> and 10.8{ % }<SUB>-6.3</SUB><SUP>+11.3</SUP>, respectively. For the early-type nucleated galaxies, we are able to carry out a controlled comparison with a parent sample of non-nucleated galaxies covering the same stellar mass range, again finding no statistically significant difference in the active fraction. Taken at face value, our findings suggest that the presence of an NSC does not facilitate or enhance accretion-powered emission from a nuclear supermassive black hole. This is true even for late-type nucleated galaxies, home to bluer NSCs and arguably larger gas reservoirs.

Supermassive black holes (BHs) are fundamental components of galaxies, as demonstrated by the correlations between BH mass and large-scale galaxy properties. However, these scaling relations are based on BH mass measurements in a galaxy sample that is significantly biased relative to the overall galaxy population. We propose to enhance the diversity of galaxies with BH mass measurements using a combination of adaptive optics kinematics and HST imaging. Our proposal focuses on the first six galaxies observed as part of a recently approved Gemini Large Program to measure BH masses in 31 galaxies. HST imaging is required for (1) the creation of high-resolution stellar mass models, and (2) the determination of the adaptive optics point spread function; both are essential for measuring accurate BH masses. Immediate observations are needed to guide our approved future Gemini observations and to develop and refine our BH mass estimation pipeline. The six galaxies in the present proposal have a wide range of galaxy sizes and luminosities, significantly expanding the types of galaxies with known BH masses. This data is crucial for understanding the underlying physics driving the BH -- galaxy scaling relations and their scatter.

The existence of medium-sized black holes has long been debated. Such an object has now been discovered in the centre of a dense cluster of stars, potentially enhancing our understanding of all black holes. See Letter p.203

Mrk 1216 is a nearby, early-type galaxy with a small effective radius of 2.8 kpc and a large stellar velocity dispersion of 308 km s<SUP>-1</SUP> for its K-band luminosity of 1.4× {10}<SUP>11</SUP> {L}<SUB>⊙ </SUB>. Using integral field spectroscopy assisted by adaptive optics from Gemini North, we measure spatially resolved stellar kinematics within ∼450 pc of the galaxy nucleus. The galaxy exhibits regular rotation with velocities of ±180 km s<SUP>-1</SUP> and a sharply peaked velocity dispersion profile that reaches 425 km s<SUP>-1</SUP> at the center. We fit axisymmetric, orbit-based dynamical models to the combination of these high angular resolution kinematics, large-scale kinematics extending to roughly three effective radii, and Hubble Space Telescope imaging, resulting in a constraint of the mass of the central black hole in Mrk 1216. After exploring several possible sources of systematics that commonly affect stellar-dynamical black hole mass measurements, we find a black hole mass of {M}<SUB>{BH</SUB>}=(4.9+/- 1.7)× {10}<SUP>9</SUP> {M}<SUB>⊙ </SUB> and an H-band stellar mass-to-light ratio of {{{Upsilon }}}<SUB>H</SUB>=1.3+/- 0.4 {{{Upsilon }}}<SUB>⊙ </SUB> (1σ uncertainties). Mrk 1216 is consistent with the local black hole mass-stellar velocity dispersion relation, but is a factor of ∼5-10 larger than expectations from the black hole mass-bulge luminosity and black hole mass-bulge mass correlations when conservatively using the galaxy’s total luminosity or stellar mass. This behavior is quite similar to the extensively studied compact galaxy NGC 1277. Resembling the z∼ 2 quiescent galaxies, Mrk 1216 may be a passively evolved descendant, and perhaps reflects a previous era when galaxies contained over-massive black holes relative to their bulge luminosities/masses, and the growth of host galaxies had yet to catch up.

Over the past decade it has become increasingly clear that supermassive black holes are essential components of galaxies, as demonstrated by the correlations connecting black hole masses and large-scale galaxy properties. Gaining a deeper understanding of the physical mechanisms that drive such relations requires the measurement of black holes in a wider range of galaxy types with diverse evolutionary histories. In this talk, we focus on the nearby, early-type, compact galaxy Mrk 1216. Using integral field spectroscopy assisted by adaptive optics from the Gemini North telescope and Hubble Space Telescope imaging observations, along with orbit-based dynamical models, we find a black hole mass of 5 billion solar masses. The black hole in Mrk 1216 is well above the expectations from the local black hole mass - bulge luminosity relation. With remarkable similarities to the z~2 quiescent galaxies, Mrk 1216 may be a passively evolved descendant, and perhaps reflects a previous time when galaxies contained over-massive black holes and the growth of host galaxies had yet to catch up.

The frequency of dual AGNs at low galaxy/black hole mass is poorly constrained. Thus we lack a full physical understanding of the connection between galaxy mergers and AGN activity and therefore merger-driven feedback. In particular, it is unknown whether or not LLAGN can be triggered by mergers instead of only by stochastic processes. We will address this with a 50 ksec observation to test for a dual AGN in SDSS J0914+0853, a low-mass (MBH 10^6.3), dual LLAGN candidate based on serendipitous, shallow Chandra imaging. The 15-ksec data showed two X-ray sources, but the nature of the secondary source is ambiguous because of 10% pile-up and potential PSF artifacts. With deeper, short-frame-rate Chandra observations at a new roll angle, we can unambiguously determine if the secondary is real.

Observational constraints of the relativistic jets from black holes have largely come from the most powerful and extended jets, leaving the nature of the low-luminosity jets a mystery. M81<SUP>*</SUP> is one of the nearest low-luminosity jets and it emitted an extremely large radio flare in 2011, allowing us to study compact core emission with unprecedented sensitivity and linear resolution. Using a multiwavelength campaign, we were able to track the flare as it re-brightened and became optically thick. Simultaneous X-ray observations indicated that the radio re-brightening was preceded by a low-energy X-ray flare at least 12 days earlier. Associating the time delay (t<SUB>delay</SUB>) between the two bands with the cooling time in a synchrotron flare, we find that the magnetic field strength was 1.9 < B < 9.2 G, which is consistent with magnetic field estimate from spectral energy distribution modelling, B < 10.2 G. In addition, Very Long Baseline Array observations at 23 GHz clearly illustrate a discrete knot moving at a low relativistic speed of v<SUB>app</SUB>/c = 0.51 +/- 0.17 associated with the initial radio flare. The observations indicate radial jet motions for the first time in M81<SUP>*</SUP>. This has profound implications for jet production, as it means radial motion can be observed in even the lowest-luminosity AGN, but at slower velocities and smaller radial extents (≈10<SUP>4</SUP> R<SUB>G</SUB>).

We obtained high angular resolution spectroscopy of NGC 1277 using the Near-infrared Integral Field Spectrometer (NIFS) with the ALTtitude conjugate Adaptive optics for the InfraRed system on the Gemini North telescope. The observations were taken as part of program GN-2011B-Q-27 over the course of four nights, spanning from 2012 October 30 to 2012 December 27. We observed NGC 1277 using 600s object-sky-object exposures with the H+K filter and K grating centered on 2.2μm. <P />(1 data file).

We investigate the compact, early-type galaxy NGC 1281 with integral field unit observations to map the stellar line-of-sight velocity distribution (LOSVD) out to five effective radii and construct orbit-based dynamical models to constrain its dark and luminous matter content. Under the assumption of mass-follows-light, the H-band stellar mass-to-light ratio (M/L) is Υ<SUB>⋆</SUB> = 2.7 ± 0.1 Υ<SUB>⊙</SUB>, and higher than expected from our stellar population synthesis fits with either a canonical Kroupa (Υ<SUB>⋆</SUB> = 1.3 Υ<SUB>⊙</SUB>) or Salpeter (Υ<SUB>⋆</SUB> = 1.7 Υ<SUB>⊙</SUB>) stellar initial mass function. Such models also cannot reproduce the details of the LOSVD. Models with a dark halo recover the kinematics well and indicate that NGC 1281 is dark matter dominated, making up ∼ 90 per cent of the total enclosed mass within the kinematic bounds. Parametrized as a spherical NFW profile, the dark halo mass is 11.5 ≤ log(M<SUB>DM</SUB>/M<SUB>⊙</SUB>) ≤ 11.8 and the stellar M/L is 0.6 ≤ Υ<SUB>⋆</SUB>/Υ<SUB>⊙</SUB> ≤ 1.1. However, this M/L is lower than predicted by its old stellar population. Moreover, the halo mass within the kinematic extent is 10 times larger than expected based on Λ-cold-dark-matter predictions, and an extrapolation yields cluster-sized dark halo masses. Adopting Υ<SUB>⋆</SUB> = 1.7 Υ<SUB>⊙</SUB> yields more moderate dark halo virial masses, but these models fit the kinematics worse. A non-NFW model might solve the discrepancy between the unphysical consequences of the best-fitting dynamical models and models based on more reasonable assumptions for the dark halo and stellar M/L, which are disfavoured according to our parameter estimation.

The brightest cluster galaxy in Abell 2261 (BCG2261) has an exceptionally large, flat, and asymmetric core, thought to have been shaped by a binary supermassive black hole inspiral and subsequent gravitational recoil. BCG2261 should contain a 10^10 Msun black hole, but it lacks the central cusp that should mark such a massive black hole. Based on the presence of central radio emission, we have explored the core of this galaxy with HST and the VLA to identify the presence and location of the active nucleus in this galaxy's core. We present our exploration of whether this system in fact contains direct evidence of a recoiling binary supermassive black hole. A recoiling core in this system would represent a pointed observational test of three preeminent theoretical predictions: that scouring forms cores, that SMBHs may recoil after coalescence, and that recoil can strongly influence core formation and morphology.

The nearby lenticular galaxy NGC 1277 is thought to host one of the largest black holes known, however the black hole mass measurement is based on low spatial resolution spectroscopy. In this paper, we present Gemini Near-infrared Integral Field Spectrometer observations assisted by adaptive optics. We map out the galaxy's stellar kinematics within ∼440 pc of the nucleus with an angular resolution that allows us to probe well within the region where the potential from the black hole dominates. We find that the stellar velocity dispersion rises dramatically, reaching ∼550 km s<SUP>-1</SUP> at the center. Through orbit-based, stellar-dynamical models we obtain a black hole mass of (4.9 ± 1.6) × 10<SUP>9</SUP> M<SUB>⊙</SUB> (1σ uncertainties). Although the black hole mass measurement is smaller by a factor of ∼3 compared to previous claims based on large-scale kinematics, NGC 1277 does indeed contain one of the most massive black holes detected to date, and the black hole mass is an order of magnitude larger than expectations from the empirical relation between black hole mass and galaxy luminosity. Given the galaxy's similarities to the higher redshift (z ∼ 2) massive quiescent galaxies, NGC 1277 could be a relic, passively evolving since that period. A population of local analogs to the higher redshift quiescent galaxies that also contain over-massive black holes may suggest that black hole growth precedes that of the host galaxy.

Tidal forces close to massive black holes can violently disrupt stars that make a close approach. These extreme events are discovered via bright X-ray and optical/ultraviolet flares in galactic centres. Prior studies based on modelling decaying flux trends have been able to estimate broad properties, such as the mass accretion rate. Here we report the detection of flows of hot, ionized gas in high-resolution X-ray spectra of a nearby tidal disruption event, ASASSN-14li in the galaxy PGC 043234. Variability within the absorption-dominated spectra indicates that the gas is relatively close to the black hole. Narrow linewidths indicate that the gas does not stretch over a large range of radii, giving a low volume filling factor. Modest outflow speeds of a few hundred kilometres per second are observed; these are below the escape speed from the radius set by variability. The gas flow is consistent with a rotating wind from the inner, super-Eddington region of a nascent accretion disk, or with a filament of disrupted stellar gas near to the apocentre of an elliptical orbit. Flows of this sort are predicted by fundamental analytical theory and more recent numerical simulations.

The basics of binary-supermassive-black hole accretion is observationally unconstrained. Without constraints, we are unable to make sound predictions about electromagnetic counterparts to gravitational wave events. We can finally test simulations of circum-binary accretion in PSO J334.2028+01.4075, a strong binary AGN candidate recently discovered by Liu et al. (2015). The two most basic set of predictions from simulations of circum-binary accretion models differ on whether the inner region of the accretion disk is mostly empty (a ``cavity'') or if there is substantial accretion onto one or both of the members of the binary. The two predictions differ by orders of magnitude in X-ray flux and thus allow a clear test with a 40 ksec Chandra observation.

The Swift Galactic Plane Survey is tiling 240 square degrees of the Galactic plane, from -60<l<60 and -1<b<1. Each exposure is approximately 500 seconds in duration, and includes simultaneous XRT (0.3-10keV) and UVOT/UVM2 images (2000-2500Å). All values reported herein should be considered as preliminary, a comprehensive analysis will be presented in Reynolds et al. (2013, in prep). <P />Sources are divided into those detected at a significance of greater than 3 sigma (189 in total - top) and 2-3 sigma (59 in total - bottom). <P />(1 data file).

Reverberation-mapping-based scaling relations are often used to estimate the masses of black holes from single-epoch spectra of active galactic nuclei (AGNs). While the radius-luminosity relation that is the basis of these scaling relations is determined using reverberation mapping of the Hβ line in nearby AGNs, the scaling relations are often extended to use other broad emission lines, such as Mg ii, in order to get black hole masses at higher redshifts when Hβ is redshifted out of the optical waveband. However, there is no radius-luminosity relation determined directly from Mg ii. Here, we present an attempt to perform reverberation mapping using Mg ii in the well-studied nearby Seyfert 1 NGC 5548. We used Swift to obtain UV grism spectra of NGC 5548 once every two days from 2013 April to September. Concurrent photometric UV monitoring with Swift provides a well determined continuum light curve that shows strong variability. The Mg ii emission line, however, is not strongly correlated with the continuum variability, and there is no significant lag between the two. We discuss these results in the context of using Mg ii scaling relations to estimate high-redshift black hole masses.

We present a dynamical analysis to infer the structural parameters and properties of the two nearby, compact, high-velocity dispersion galaxies MRK 1216 and NGC 1277. Combining deep Hubble Space Telescope imaging, wide-field integral field unit stellar kinematics, and complementary long-slit spectroscopic data out to three effective radii, we construct orbit-based models to constrain their black hole masses, dark matter content and stellar mass-to-light ratios. We obtain a black hole mass of log(M<SUB>•</SUB>/M<SUB>⊙</SUB>) = 10.1_{-0.2}^{+0.1} for NGC 1277 and an upper limit of log(M<SUB>•</SUB>/M<SUB>⊙</SUB>) = 10.0 for MRK 1216, within 99.7 per cent (3σ) confidence. The stellar mass-to-light ratios span a range of Υ<SUB>V</SUB> = 6.5_{-1.5}^{+1.5} in NGC 1277 and Υ<SUB>H</SUB> = 1.8_{-0.8}^{+0.5} in MRK 1216 and are in good agreement with single stellar population models of a single power-law Salpeter initial mass function. Even though our models do not place strong constraints on the dark halo parameters, they suggest that dark matter is a necessary ingredient in MRK 1216, with a dark matter contribution of 22^{+30}_{-20} per cent to the total mass budget within one effective radius. NGC 1277, on the other hand, can be reproduced without the need for a dark halo, and a maximal dark matter fraction of 13 per cent within the same radial extent. In addition, we investigate the orbital structures of both galaxies, which are rotationally supported and consistent with photometric multi-Sérsic decompositions, indicating that these compact objects do not host classical, non-rotating bulges formed during recent (z ≤ 2) dissipative events or through violent relaxation. Finally, both MRK 1216 and NGC 1277 are anisotropic, with a global anisotropy parameter δ of 0.33 and 0.58, respectively. While MRK 1216 follows the trend of fast-rotating, oblate galaxies with a flattened velocity dispersion tensor in the meridional plane of the order of β<SUB>z</SUB> ∼ δ, NGC 1277 is highly tangentially anisotropic and seems to belong kinematically to a distinct class of objects.

Located in the Perseus cluster, NGC 1271 is an early-type galaxy with a small effective radius of 2.2 kpc and a large bulge stellar velocity dispersion of 276 km s<SUP>-1</SUP> for its K-band luminosity of 8.9× {10}<SUP>10</SUP> {L}<SUB>⊙ </SUB>. We present a mass measurement for the black hole in this compact, high-dispersion galaxy using observations from the Near-infrared Integral Field Spectrometer on the Gemini North telescope assisted by laser guide star adaptive optics, large-scale integral field unit observations with PPAK at the Calar Alto Observatory, and Hubble Space Telescope WFC3 imaging observations. We are able to map out the stellar kinematics both on small spatial scales, within the black hole sphere of influence, and on large scales that extend out to four times the galaxy’s effective radius. We find that the galaxy is rapidly rotating and exhibits a sharp rise in the velocity dispersion. Through the use of orbit-based stellar dynamical models, we determine that the black hole has a mass of ({3.0}<SUB>-1.1</SUB><SUP>+1.0</SUP>)× {10}<SUP>9</SUP> {M}<SUB>⊙ </SUB> and the H-band stellar mass-to-light ratio is {1.40}<SUB>-0.11</SUB><SUP>+0.13</SUP> {Upsilon }<SUB>⊙ </SUB> (1σ uncertainties). NGC 1271 occupies the sparsely populated upper end of the black hole mass distribution but is very different from the brightest cluster galaxies (BCGs) and giant elliptical galaxies that are expected to host the most massive black holes. Interestingly, the black hole mass is an order of magnitude larger than expectations based on the galaxy’s bulge luminosity but is consistent with the mass predicted using the galaxy’s bulge stellar velocity dispersion. More compact, high-dispersion galaxies need to be studied using high spatial resolution observations to securely determine black hole masses, as there could be systematic differences in the black hole scaling relations between these types of galaxies and the BCGs/giant ellipticals, thereby implying different pathways for black hole and galaxy growth.

The HET Massive Galaxy Survey (HETMGS) ran from 2010 April to 2013 August. The total survey consists of 1022 galaxies, with 1265 long-slit spectra taken over 550hr with the Hobby-Eberly Telescope (HET). All the observations were taken with the Marcario Low Resolution Spectrograph (LRS; in 4200-7400Å range). The typical spatial resolution of the observations is 2.5" FWHM. <P />(1 data file).

We have conducted an optical long-slit spectroscopic survey of 1022 galaxies using the 10 m Hobby-Eberly Telescope (HET) at McDonald Observatory. The main goal of the HET Massive Galaxy Survey (HETMGS) is to find nearby galaxies that are suitable for black hole mass measurements. In order to measure accurately the black hole mass, one should kinematically resolve the region where the black hole dominates the gravitational potential. For most galaxies, this region is much less than an arcsecond. Thus, black hole masses are best measured in nearby galaxies with telescopes that obtain high spatial resolution. The HETMGS focuses on those galaxies predicted to have the largest sphere-of-influence, based on published stellar velocity dispersions or the galaxy fundamental plane. To ensure coverage over galaxy types, the survey targets those galaxies across a face-on projection of the fundamental plane. We present the sample selection and resulting data products from the long-slit observations, including central stellar kinematics and emission line ratios. The full data set, including spectra and resolved kinematics, is available online. Additionally, we show that the current crop of black hole masses are highly biased toward dense galaxies and that especially large disks and low dispersion galaxies are under-represented. This survey provides the necessary groundwork for future systematic black hole mass measurement campaigns.

We study the X-ray properties of a sample of 14 optically selected low-mass active galactic nuclei (AGN) whose masses lie within the range 10<SUP>5</SUP>-2 × 10<SUP>6</SUP> M<SUB>⊙</SUB> with XMM-Newton. Only six of these low-mass AGN have previously been studied with sufficient quality X-ray data, thus, we have more than double the number of low-mass AGN observed by XMM-Newton with the addition of our sample. We analyse their X-ray spectral properties and variability and compare the results to their more massive counterparts. The presence of a soft X-ray excess is detectable in all five objects which were not background dominated at 2-3 keV. Combined with previous studies, this gives a total of eight low-mass AGN with a soft excess. The low-mass AGN exhibit rapid, short-term variability (hundreds to thousands of seconds) and long-term variability (months to years). There is a well-known anticorrelation between black hole mass and variability amplitude (normalized excess variance). Comparing our sample of low-mass AGN with this relation we find that all of our sample lie below an extrapolation of the linear relation. Such a flattening of the relation at low masses (below ∼10<SUP>6</SUP> M<SUB>⊙</SUB>) is expected if the variability in all AGN follows the same shape power spectrum with a break frequency that is dependent on mass. Finally, we also found two objects that show significant absorption in their X-ray spectrum, indicative of type 2 objects, although they are classified as type 1 AGN based on optical spectra.

Accreting black holes are observed to launch relativistic, collimated jets of matter and radiation. In some sources, discrete ejections have been detected with highly relativistic velocities. These particular sources typically have very high mass accretion rates, while sources lower knot velocities are predominantly associated with black holes with relatively low mass accretion rates. We quantify this behavior by examining knot velocity with respect to X-ray luminosity, a proxy for mass accretion rate onto the black hole. We find a positive correlation between the mass-scaled X-ray luminosity and jet knot velocity. In addition, we find evidence that the jet velocity is also a function of polar angle, supporting the "spine-sheath" model of jet production. Our results reveal a fundamental aspect of how accretion shapes mechanical feedback from black holes into their host environments.

The relation between central black hole mass and stellar spheroid velocity dispersion (the M-Sigma relation) is one of the best-known correlations linking black holes and their host galaxies. However, there is a large amount of scatter at the low-mass end, indicating that the processes that relate black holes to lower-mass hosts are not straightforward. Some of this scatter can be explained by inclination effects; contamination from disk stars along the line of sight can artificially boost velocity dispersion measurements by 30%. Using state of the art simulations, we have developed a correction factor for inclination effects based on purely observational quantities. We present the results of applying these factors to observed samples of galaxies and discuss the effects on the M-Sigma relation.

We report on a Chandra observation of the candidate tidal disruption flare ASASSN-14li (Jose et al. 2014, ATEL #6777). The high flux from this nearby event offered an excellent opportunity to search for lines that might illuminate the aftermath of the disruption.

We report on the use of the 0th order images from the Chandra HRC-LETG DDT observations of ASSASN-14li (Miller et al., 2014; ATel #6800) to locate this likely tidal disruption event (TDE; Jose et al., 2014; ATel #6777) with respect to its host nucleus.

We report on a 94 ks observation of the TDE candidate ASASSN-14li, obtained on 8 December 2014 with XMM-Newton. The high resolution first-order RGS spectra show a number of significant absorption features in the 20-40 Angstroms band, most notably at 24.6, 25.25, 27.9, 29.9, 31.1, and 32.9 Angstroms.

The relation of central black hole mass and stellar spheroid velocity dispersion (the M-σ relation) is one of the best-known and tightest correlations linking black holes and their host galaxies. There has been much scrutiny concerning the difficulty of obtaining accurate black hole measurements, and rightly so; however, it has been taken for granted that measurements of velocity dispersion are essentially straightforward. We examine five disc galaxies from cosmological SPH simulations and find that line-of-sight effects due to galaxy orientation can affect the measured σ<SUB>los</SUB> by 30 per cent, and consequently black hole mass predictions by up to 1.0 dex. Face-on orientations correspond to systematically lower velocity dispersion measurements, while more edge-on orientations give higher velocity dispersions, due to contamination by disc stars when measuring line-of-sight quantities. We caution observers that the uncertainty of velocity dispersion measurements is at least 20 km s<SUP>-1</SUP>, and can be much larger for moderate inclinations. This effect may account for some of the scatter in the locally measured M-σ relation, particularly at the low-mass end. We provide a method for correcting observed σ<SUB>los</SUB> values for inclination effects based on observable quantities.

We will measure the X-ray flux and radio continuum of 7 ultramassive BHs (M>3e9) to test competing models of the fundamental plane (FP) of BH accretion. The FP relates the X-ray, radio, and mass of an accreting BH, and demonstrates there is a connection between BH inflow and outflow. The FP is derived mostly from BHs with masses under 2e9. It is not clear if the FP holds for the largest BHs. The 2 ways to create the FP, with only SMBHs OR jointly with SMBHs and stellar BHs, differ by 100 for the largest BHs. Only with Chandra we can separate corona and AGN to determine it. Coronae around huge BHs are critical in limiting feeding so that we can understand the gas supply around and accretion onto the largest BHs.

We put active galactic nuclei (AGNs) with low-mass black holes on the fundamental plane of black hole accretion—the plane that relates X-ray emission, radio emission, and mass of an accreting black hole—to test whether or not the relation is universal for both stellar-mass and supermassive black holes. We use new Chandra X-ray and Very Large Array radio observations of a sample of black holes with masses less than 10<SUP>6.3</SUP> M <SUB>⊙</SUB>, which have the best leverage for determining whether supermassive black holes and stellar-mass black holes belong on the same plane. Our results suggest that the two different classes of black holes both belong on the same relation. These results allow us to conclude that the fundamental plane is suitable for use in estimating supermassive black hole masses smaller than ~10<SUP>7</SUP> M <SUB>⊙</SUB>, in testing for intermediate-mass black holes, and in estimating masses at high accretion rates.

Understanding how black holes accrete and supply feedback to their environment is one of the outstanding challenges of modern astrophysics. Swift J1910.2-0546 is a candidate black hole low-mass X-ray binary that was discovered in 2012 when it entered an accretion outburst. To investigate the binary configuration and the accretion morphology, we monitored the evolution of the outburst for sime3 months at X-ray, UV, optical (B, V, R, I), and near-infrared (J, H, K) wavelengths using Swift and SMARTS. The source evolved from a hard to a soft X-ray spectral state with a relatively cold accretion disk that peaked at sime0.5 keV. A Chandra/HETG spectrum obtained during this soft state did not reveal signatures of an ionized disk wind. Both the low disk temperature and the absence of a detectable wind could indicate that the system is viewed at relatively low inclination. The multi-wavelength light curves revealed two notable features that appear to be related to X-ray state changes. First, a prominent flux decrease was observed in all wavebands ~= 1-2 weeks before the source entered the soft state. This dip occurred in (0.6-10 keV) X-rays ~= 6 days later than at longer wavelengths, which could possibly reflect the viscous timescale of the disk. Second, about two weeks after the source transitioned back into the hard state, the UV emission significantly increased while the X-rays steadily decayed. We discuss how these observations may reflect changes in the accretion morphology, perhaps related to the quenching/launch of a jet or the collapse/recovery of a hot flow.

We determine the mass of the nuclear black hole (M) in NGC 3706, an early-type galaxy with a central surface brightness minimum arising from an apparent stellar ring, which is misaligned with respect to the galaxy's major axis at larger radii. We fit new HST/STIS and archival data with axisymmetric orbit models to determine M, mass-to-light ratio (Upsilon<SUB> V </SUB>), and dark matter halo profile. The best-fit model parameters with 1σ uncertainties are M= (6.0^{+0.7}_{-0.9}) times 10^8 {{M}}_{odot } and Upsilon _V = 6.0 +/- 0.2 {{M}}_{odot } {L}_{{odot },V}^{-1} at an assumed distance of 46 Mpc. The models are inconsistent with no black hole at a significance of Δχ<SUP>2</SUP> = 15.4 and require a dark matter halo to adequately fit the kinematic data, but the fits are consistent with a large range of plausible dark matter halo parameters. The ring is inconsistent with a population of co-rotating stars on circular orbits, which would produce a narrow line-of-sight velocity distribution (LOSVD). Instead, the ring's LOSVD has a small value of |V|/σ, the ratio of mean velocity to velocity dispersion. Based on the observed low |V|/σ, our orbit modeling, and a kinematic decomposition of the ring from the bulge, we conclude that the stellar ring contains stars that orbit in both directions. We consider potential origins for this unique feature, including multiple tidal disruptions of stellar clusters, a change in the gravitational potential from triaxial to axisymmetric, resonant capture and inclining of orbits by a binary black hole, and multiple mergers leading to gas being funneled to the center of the galaxy. <P />Based on observations made with the Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with GO proposal 8687.

We calculate the observability of a black hole (BH) accretion disk with a gap or a hole created by a secondary BH embedded in the disk. We find that for an interesting range of parameters of BH masses 10^6-10^9 M⊙), orbital separation 1 AU to ~0.1 pc), and gap width (10-190 disk scale heights), the missing thermal emission from a gap manifests itself in an observable decrement in the spectral energy distribution (SED). The change in slope in the broken power law is strongly dependent on the width of the gap in the accretion disk, which in turn is uniquely determined by the mass ratio of the BHs (under our assumptions), such that it scales roughly as q^(5/12). Thus, one can use spectral observations of the continuum of bright AGNs to infer not only the presence of a closely separated BH binary, but also the mass ratio. When the BH merger opens an entire hole (or cavity) in the inner disk, the broadband SED of the AGNs or quasar may serve as a diagnostic. We note future directions for this research.

Correlations linking the mass of the black hole in the centers of galaxies to bulge properties have been clearly established over the past decade; however there still remain major open questions, particularly concerning the sparsely populated upper end of the black hole mass distribution. Through a large survey with the Hobby Eberly Telescope at McDonald Observatory, we have identified a sample of ideal galaxies for studying the upper end of the black hole mass scaling relations. These galaxies are compact, rapidly rotating, and have low luminosities for their very large stellar velocity dispersions, in sharp contrast to the objects typically found at the high end of the black holes mass - bulge relationships. In this talk, we focus on one galaxy in the sample: the nearby S0 galaxy NGC 1271. We present laser guide star adaptive optics observations of NGC 1271 with the integral field spectrograph NIFS on the Gemini North telescope. By combining the high spatial resolution stellar kinematics measured from the NIFS observations with imaging and large-scale stellar kinematics, we construct orbit-based stellar dynamical models. We will present results of the dynamical modeling, emphasizing the constraints on the black hole mass, and place NGC 1271 on the black hole mass - host galaxy relationships.

Simultaneous observations of X-rays and radio luminosities have been well studied in accreting stellar-mass black holes. These observations are performed in order to understand how mass accretion rates and jetted outflows are linked in these individual systems. Such contemporaneous studies in supermassive black holes (SMBH) are harder to perform, as viscous times scale linearly with mass. However, as NGC 4395 is the lowest known mass Seyfert galaxy, we have used it to examine the simultaneous X-ray (Swift) and radio (Very Large Array) correlation in a SMBH in a reasonably timed observing campaign. We find that the intrinsic X-ray variability is stronger than the radio variability, and that the fluxes are only weakly or tentatively coupled, similar to prior results obtained in NGC 4051. If the corona and the base of the jet are one and the same, this may suggest that the corona in radio-quiet active galactic nucleus filters disk variations, only transferring the strongest and/or most sustained variations into the jet. Further, when both NGC 4395 and NGC 4051 are placed on the stellar-mass L<SUB>X</SUB> -L<SUB>R</SUB> plane, they appear to reside on the steeper L<SUB>X</SUB> -L<SUB>R</SUB> track. This suggests that SMBHs also follow two distinct tracks just as stellar-mass black holes do, and supports the idea that the same physical disk-jet mechanisms are at play across the mass scale.

Simultaneous observations of X-rays and radio luminosities have been well studied in accreting stellar-mass black holes. These observations are performed in order to understand how mass accretion rates and jetted outflows are linked in these individual systems. Such contemporaneous studies in supermassive black holes (SMBH) are harder to perform, as viscous times scale linearly with mass. However, as NGC 4395 is the lowest known mass Seyfert galaxy, we have used it to examine the simultaneous X-ray (Swift) and radio (Very Large Array) correlation in a SMBH in a reasonably timed observing campaign. We find that the intrinsic X-ray variability is stronger than the radio variability, and that the fluxes are only weakly or tentatively coupled, similar to prior results obtained in NGC 4051. If the corona and the base of the jet are one and the same, this may suggest that the corona in radio-quiet active galactic nucleus filters disk variations, only transferring the strongest and/or most sustained variations into the jet. Further, when both NGC 4395 and NGC 4051 are placed on the stellar-mass L<SUB>X</SUB> -L<SUB>R</SUB> plane, they appear to reside on the steeper L<SUB>X</SUB> -L<SUB>R</SUB> track. This suggests that SMBHs also follow two distinct tracks just as stellar-mass black holes do, and supports the idea that the same physical disk-jet mechanisms are at play across the mass scale.

We examine the role of spin in launching jets from compact objects across the mass scale. Our work includes 3 different Seyfert samples with a total of 37 unique Seyferts, as well as 11 stellar-mass black holes, and 13 neutron stars. We find that when the Seyfert reflection lines are modeled with simple Gaussian line features (a crude proxy for inner disk radius and therefore spin), only a slight inverse correlation is found between the Doppler-corrected radio luminosity at 5 GHz (a proxy for jet power) and line width. When the Seyfert reflection features are fit with more relativistically blurred disk reflection models that measure spin, there is a tentative positive correlation between the Doppler-corrected radio luminosity and the spin measurement. Further, when we include stellar-mass black holes in the sample, to examine the effects across the mass scale, we find a slightly stronger correlation with radio luminosity per unit mass and spin, at a marginal significance (2.3σ confidence level). Finally, when we include neutron stars, in order to probe lower spin values, we find a positive correlation (3.3σ confidence level) between radio luminosity per unit mass and spin. Although tentative, these results suggest that spin may have a role in determining the jet luminosity. In addition, we find a slightly more significant correlation (4.4σ and 4.1σ confidence level, respectively) between radio luminosity per bolometric luminosity and spin, as well as radio luminosity corrected for the fundamental plane (i.e., log (nu L_R/L_{Bol}^{0.67}/M_{BH}^{0.78})) and spin, using our entire sample of black holes and neutrons stars. Again, although tentative, these relations point to the possibility that the mass accretion rate, i.e., bolometric luminosity, is also important in determining the jet luminosity, in addition to spin. Our analysis suggests that mass accretion rate and disk or coronal magnetic field strength may be the "throttle" in these compact systems, to which the Eddington limit and spin may set the maximum jet luminosity that can be achieved.

The Swift Galactic Plane Survey team report the detection of 248 point-like X-ray sources (0.3 - 10 keV) in observations covering the final 40% of our survey area (see also Atel #3951, #4318). The listed sources are those we consider to be robust detections at the current time. A comprehensive analysis with final source properties will be presented in Reynolds et al. (2013) in prep.

We present X-ray and radio observations of the new Galactic supernova remnant (SNR) G306.3-0.9, recently discovered by Swift. Chandra imaging reveals a complex morphology, dominated by a bright shock. The X-ray spectrum is broadly consistent with a young SNR in the Sedov phase, implying an age of 2500 yr for a distance of 8 kpc, plausibly identifying this as one of the 20 youngest Galactic SNRs. Australia Telescope Compact Array (ATCA) imaging reveals a prominent ridge of radio emission that correlates with the X-ray emission. We find a flux density of ~ 160 mJy at 1 GHz, which is the lowest radio flux recorded for a Galactic SNR to date. The remnant is also detected at 24 microns, indicating the presence of irradiated warm dust. The data reveal no compelling evidence for the presence of a compact stellar remnant.

We examine the role of spin in launching jets from compact objects across the mass scale. Our work includes five different Seyfert samples with a total of 39 unique Seyferts, as well as 11 stellar-mass black holes, and 13 neutron stars. We find that when the Seyfert reflection lines are modeled with simple Gaussian line features, only a slight inverse correlation is found between the line width and radio luminosity. When the Seyfert reflection features are fit with more realistic models, there is a tentative positive correlation between the spin measurement and the radio luminosity. Further, when we include stellar-mass black holes in the sample, to examine the effects across the mass scale, we find an even stronger correlation with spin and radio luminosity per mass, at a marginal significance (2.3 sigma confidence level). Finally, when we include neutron stars, in order to probe lower spin values, we find a strong correlation (4.3 sigma confidence level) between spin and radio luminosity per mass. This suggests that spin does have a role in determining the jet luminosity. In addition, we find a slightly more significant correlation (4.6 sigma confidence level) between spin and radio luminosity per bolometric correlation, using our entire sample of black holes and neutrons stars. This points to the idea that mass accretion rate, i.e. bolometric luminosity, is also important in determining the jet luminosity, in addition to spin. The mass accretion and magnetic field strength may be the ``throttle" in these compact systems, to which the Eddington limit and spin may set the maximum jet luminosity that can be achieved.

Supermassive black holes are known to exist at the center of most galaxies with sufficient stellar mass. In the local universe, it is possible to infer their properties from the surrounding stars or gas. However, at high redshifts we require active, continuous accretion to infer the presence of the SMBHs, which often comes in the form of long-term accretion in active galactic nuclei. Supermassive black holes can also capture and tidally disrupt stars orbiting nearby, resulting in bright flares from otherwise quiescent black holes. Here, we report on a 200-second x-ray quasi-periodicity around a previously dormant SMBH located in the center of a galaxy at redshift z = 0.3534. This result may open the possibility of probing general relativity beyond our local universe.

We present X-ray and radio observations of the new Galactic supernova remnant (SNR) G306.3-0.9, recently discovered by Swift. Chandra imaging reveals a complex morphology, dominated by a bright shock. The X-ray spectrum is broadly consistent with a young SNR in the Sedov phase, implying an age of 2500 yr for a distance of 8 kpc, plausibly identifying this as one of the 20 youngest Galactic SNRs. Australia Telescope Compact Array imaging reveals a prominent ridge of radio emission that correlates with the X-ray emission. We find a flux density of ~160 mJy at 1 GHz, which is the lowest radio flux recorded for a Galactic SNR to date. The remnant is also detected at 24 μm, indicating the presence of irradiated warm dust. The data reveal no compelling evidence for the presence of a compact stellar remnant.

We present X-ray and radio observations of the new Galactic supernova remnant (SNR) G306.3-0.9, recently discovered by Swift. Chandra imaging reveals a complex morphology, dominated by a bright shock. The X-ray spectrum is broadly consistent with a young SNR in the Sedov phase, implying an age of 2500 yr for a distance of 8 kpc, plausibly identifying this as one of the 20 youngest Galactic SNRs. Australia Telescope Compact Array imaging reveals a prominent ridge of radio emission that correlates with the X-ray emission. We find a flux density of ~160 mJy at 1 GHz, which is the lowest radio flux recorded for a Galactic SNR to date. The remnant is also detected at 24 μm, indicating the presence of irradiated warm dust. The data reveal no compelling evidence for the presence of a compact stellar remnant.

We present X-ray and radio observations of the new Galactic supernova remnant (SNR) G306.3-0.9, recently discovered by Swift. Chandra imaging reveals a complex morphology, dominated by a bright shock. The X-ray spectrum is broadly consistent with a young SNR in the Sedov phase, implying an age of 2500 yr for a distance of 8 kpc, plausibly identifying this as one of the 20 youngest Galactic SNRs. Australia Telescope Compact Array imaging reveals a prominent ridge of radio emission that correlates with the X-ray emission. We find a flux density of ~160 mJy at 1 GHz, which is the lowest radio flux recorded for a Galactic SNR to date. The remnant is also detected at 24 μm, indicating the presence of irradiated warm dust. The data reveal no compelling evidence for the presence of a compact stellar remnant.

We present a study of the mechanical power generated by both winds and jets across the black hole mass scale. We begin with the study of ionized X-ray winds and present a uniform analysis using Chandra grating spectra. The high-quality grating spectra facilitate the characterization of the outflow velocity, ionization, and column density of the absorbing gas. We find that the kinetic power of the winds, derived from these observed quantities, scales with increasing bolometric luminosity as log (L <SUB>wind, 42</SUB>/C<SUB>v</SUB> ) = (1.58 ± 0.07)log (L <SUB>Bol, 42</SUB>) - (3.19 ± 0.19). This suggests that supermassive black holes may be more efficient than stellar-mass black holes in launching winds, per unit filling factor, C<SUB>v</SUB> . If the black hole binary (BHB) and active galactic nucleus (AGN) samples are fit individually, the slopes flatten to α<SUP>BHB</SUP> = 0.91 ± 0.31 and α<SUP>AGN</SUP> = 0.63 ± 0.30 (formally consistent within errors). The broad fit and individual fits both characterize the data fairly well, and the possibility of common slopes may point to common driving mechanisms across the mass scale. For comparison, we examine jet production, estimating jet power based on the energy required to inflate local bubbles. The jet relation is log (L <SUB>Jet, 42</SUB>) = (1.18 ± 0.24)log (L <SUB>Bondi, 42</SUB>) - (0.96 ± 0.43). The energetics of the bubble associated with Cygnus X-1 are particularly difficult to determine, and the bubble could be a background supernova remnant. If we exclude Cygnus X-1 from our fits, then the jets follow a relation consistent with the winds, but with a higher intercept, log (L <SUB>Jet, 42</SUB>) = (1.34 ± 0.50)log (L <SUB>Bondi, 42</SUB>) - (0.80 ± 0.82). The formal consistency in the wind and jet scaling relations, when assuming that L <SUB>Bol</SUB> and L <SUB>Bondi</SUB> are both proxies for mass accretion rate, suggests that a common launching mechanism may drive both flows; magnetic processes, such as magnetohydrodynamics and magnetocentrifugal forces, are viable possibilities. We also examine winds that are moving at especially high velocities, v > 0.01c. These ultra-fast outflows tend to resemble the jets more than the winds in terms of outflow power, indicating that we may be observing a regime in which winds become jets. A transition at approximately L <SUB>Bol</SUB> ≈ 10<SUP>-2</SUP> L <SUB>Edd</SUB> is apparent when outflow power is plotted versus Eddington fraction. At low Eddington fractions, the jet power is dominant, and at high Eddington fractions, the wind power is dominant. This study allows for the total power from black hole accretion, both mechanical and radiative, to be characterized in a simple manner and suggests possible connections between winds and jets. X-ray wind data and jet cavity data will enable stronger tests.

We calculate the observable signature of a black hole (BH) accretion disk with a gap or a hole created by a secondary BH embedded in the disk. We find that for an interesting range of parameters of BH masses (~10<SUP>6</SUP>-10<SUP>9</SUP> M <SUB>⊙</SUB>), orbital separation (~1 AU to ~0.1 pc), and gap width (10-190 disk scale heights), the missing thermal emission from a gap manifests itself in an observable decrement in the spectral energy distribution (SED). We present observational diagnostics in terms of power-law forms that can be fit to line-free regions in active galactic nucleus (AGN) spectra or in fluxes from sequences of broad filters. Most interestingly, the change in slope in the broken power law is almost entirely dependent on the width of the gap in the accretion disk, which in turn is uniquely determined by the mass ratio of the BHs, such that it scales roughly as q <SUP>5/12</SUP>. Thus, one can use spectral observations of the continuum of bright AGNs to infer not only the presence of a closely separated BH binary, but also the mass ratio. When the BH merger opens an entire hole (or cavity) in the inner disk, the broadband SED of the AGNs or quasar may serve as a diagnostic. Such sources should be especially luminous in optical bands but intrinsically faint in X-rays (i.e., not merely obscured). We briefly note that viable candidates may have already been identified, though extant detailed modeling of those with high-quality data have not yet revealed an inner cavity.

Most massive galaxies have supermassive black holes at their centres, and the masses of the black holes are believed to correlate with properties of the host-galaxy bulge component. Several explanations have been proposed for the existence of these locally established empirical relationships, including the non-causal, statistical process of galaxy-galaxy merging, direct feedback between the black hole and its host galaxy, and galaxy-galaxy merging and the subsequent violent relaxation and dissipation. The empirical scaling relations are therefore important for distinguishing between various theoretical models of galaxy evolution, and they furthermore form the basis for all black-hole mass measurements at large distances. Observations have shown that the mass of the black hole is typically 0.1 per cent of the mass of the stellar bulge of the galaxy. Until now, the galaxy with the largest known fraction of its mass in its central black hole (11 per cent) was the small galaxy NGC 4486B. Here we report observations of the stellar kinematics of NGC 1277, which is a compact, lenticular galaxy with a mass of 1.2 × 10<SUP>11</SUP> solar masses. From the data, we determine that the mass of the central black hole is 1.7 × 10<SUP>10</SUP> solar masses, or 59 per cent of its bulge mass. We also show observations of five other compact galaxies that have properties similar to NGC 1277 and therefore may also contain over-massive black holes. It is not yet known if these galaxies represent a tail of a distribution, or if disk-dominated galaxies fail to follow the usual black-hole mass scaling relations.

The Swift Galactic Plane Survey team report the detection of 271 point-like X-ray sources (0.3 - 10 keV) in observations covering the next 35% of our survey area (now 60% complete; the first increment of sources, 140 detections in the first 25% of the survey area, may be found in Atel #3951). The listed sources are those we consider to be robust detections at the current time. Further source releases will occur as observations are accumulated.

Supermassive black holes (SMBHs; mass is greater than or approximately 10<SUP>5</SUP> times that of the Sun) are known to exist at the center of most galaxies with sufficient stellar mass. In the local universe, it is possible to infer their properties from the surrounding stars or gas. However, at high redshifts we require active, continuous accretion to infer the presence of the SMBHs, which often comes in the form of long-term accretion in active galactic nuclei. SMBHs can also capture and tidally disrupt stars orbiting nearby, resulting in bright flares from otherwise quiescent black holes. Here, we report on a ~200-second x-ray quasi-periodicity around a previously dormant SMBH located in the center of a galaxy at redshift z = 0.3534. This result may open the possibility of probing general relativity beyond our local universe.

We present Chandra observations of 12 galaxies that contain supermassive black holes (SMBHs) with dynamical mass measurements. Each galaxy was observed for 30 ks and resulted in a total of 68 point-source detections in the target galaxies including SMBH sources, ultraluminous X-ray sources (ULXs), and extragalactic X-ray binaries. Based on our fits of the X-ray spectra, we report fluxes, luminosities, Eddington ratios, and slope of the power-law spectrum. Normalized to the Eddington luminosity, the 2-10 keV band X-ray luminosities of the SMBH sources range from 10<SUP>-8</SUP> to 10<SUP>-6</SUP>, and the power-law slopes are centered at ~2 with a slight trend toward steeper (softer) slopes at smaller Eddington fractions, implying a change in the physical processes responsible for their emission at low accretion rates. We find 20 ULX candidates, of which 6 are likely (>90% chance) to be true ULXs. The most promising ULX candidate has an isotropic luminosity in the 0.3-10 keV band of 1.0<SUP>+0.6</SUP> <SUB>- 0.3</SUB> × 10<SUP>40</SUP> erg s<SUP>-1</SUP>.

The Swift Galactic Plane Survey team report the detection of 140 point like X-ray sources (0.3 - 10 keV) in the initial 25% of the survey. The listed sources are those we consider to be robust detections at the current time. Further source releases will occur as observations are accumulated. <P />Sources are divided into those detected at a significance of greater than 3 sigma (95 in total - top) and 2-3 sigma (55 in total - bottom).

The Swift galactic plane survey team (SGPS) report the detection of a new extended X-ray source. The source was discovered in a 1.4 ks XRT exposure on 2011 October 30th.

We present Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph observations of the galaxy NGC 4382 (M85) and axisymmetric models of the galaxy to determine mass-to-light ratio (Upsilon<SUB> V </SUB>) and central black hole mass (M <SUB>BH</SUB>). We find Upsilon<SUB> V </SUB> = 3.74 ± 0.1 M <SUB>sun</SUB>/L <SUB>sun</SUB> and M <SUB>BH</SUB> = 1.3<SUP>+5.2</SUP> <SUB>- 1.2</SUB> × 10<SUP>7</SUP> M <SUB>sun</SUB> at an assumed distance of 17.9 Mpc, consistent with no black hole. The upper limit, M <SUB>BH</SUB> < 9.6 × 10<SUP>7</SUP> M <SUB>sun</SUB>(2σ) or M <SUB>BH</SUB> < 1.4 × 10<SUP>8</SUP>(3σ), is consistent with the current M-σ relation, which predicts M <SUB>BH</SUB> = 8.8 × 10<SUP>7</SUP> M <SUB>sun</SUB> at σ<SUB> e </SUB> = 182 km s<SUP>-1</SUP>, but low for the current M - L relation, which predicts M <SUB>BH</SUB> = 7.8 × 10<SUP>8</SUP> M <SUB>sun</SUB> at L<SUB>V</SUB> = 8.9 × 10<SUP>10</SUP> L <SUB>sun, V </SUB>. HST images show the nucleus to be double, suggesting the presence of a nuclear eccentric stellar disk, analogous to the Tremaine disk in M31. This conclusion is supported by the HST velocity dispersion profile. Despite the presence of this non-axisymmetric feature and evidence of a recent merger, we conclude that the reliability of our black hole mass determination is not hindered. The inferred low black hole mass may explain the lack of nuclear activity. <P />Based on observations made with the Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with GO proposals 5999, 6587, 6633, 7468, and 9107.

The observed tight correlations between black hole mass and host galaxy properties evince a fundamental connection between their joint evolution. The key to understanding this co-evolution rests on the ability to measure the smallest black hole masses, which closely trace the formation of black holes. But, recent observational evidence suggests the smallest black holes and/or the smallest galaxies {especially pseudobulges} diverge from the scaling relations. There is therefore a pressing need: {1} to firmly establish multiple, independent measures of black hole mass in these smallest objects, and {2} to accurately determine properties of the host galaxy. Unfortunately, low AGN luminosity means that galaxy contamination is a prohibiting issue for normal ground-based measures of BH mass. But, in the UV this is not a problem allowing the use of CIV to measure BH masses through COS spectroscopy. Moreover, with WFC3 imaging we can unambiguously determine the bulge morphology and luminosity. Therefore, only with our proposed HST campaign to study 6 low-luminosity AGN will we be able to test whether or not the smallest black holes in the smallest galaxies are truly aberrations compared to their higher-mass counterparts.

The Swift Galactic Plane Survey (SGPS) is a 240 square degree survey of the Galactic plane, covering the region |b| < 1 deg and |l| < 60 deg. The survey is designed to obtain 100% overlap with the Spitzer (GLIMPSE/MIPSGAL) and Herschel (HiGal) Galactic plane surveys in the 0.3 -- 10 keV band, crucially including the dust penetrating 2 -- 10 keV hard X-ray band. In addition, we will take advantage of the multi-wavelength capabilities of Swift to obtain simultaneuous ultra-violet (UV) imaging with the UVM2 filter ( 2246 Angstrom), resulting in the first large area survey of the Galactic plane at UV wavelengths. This survey complements the ongoing and completed surveys of the Galactic plane, filling in the crucial high energy region, and will facilitate a truly multi-wavelength study of the Milky Way galaxy. <P />The survey area is 6 times larger than that previously imaged by ASCA, and the order of magnitude improvement in spatial resolution provided by the Swift X-ray telescope will enable follow-up identification of unique multi-wavelength counterparts. We will discuss the current status of the survey and present preliminary results.

We present our work on outflows in the Seyfert-1 AGN, NGC 4051. The joint study of both winds and jets allows us to address the total outflowing power and feedback of this AGN. Evidence for compact jet production is observed in the EVLA 8.4 GHz band, while the warm absorbing winds are observed in Chandra HETG spectra. Counter to the expectations of the fundamental plane of accretion, accretion power (traced by X-ray flux) and jet power (traced by radio flux) are only weakly correlated in our simultaneous EVLA and Chandra data, or perhaps even anti-correlated. This may represent a separate mode of disk-jet coupling that obtains at high Eddington fractions. Both XSTAR and Cloudy models for the X-ray warm absorbers require only two absorption zones. The closer of the two gives a wind launching radius of just 100 gravitational radii, perhaps suggesting a role for magnetic driving of the wind. Evidence for simultaneous jet and wind production is significantly different from stellar mass black holes. These results will be discussed in terms of wind and jet production across the black hole mass scale.

The fundamental plane relates the X-ray luminosity, radio luminosity, and mass of accreting BHs and demonstrates an intimate connection between BH inflow and outflow. Existing data are mostly from SMBHs with Mbh > 10^7. It is not clear whether the plane holds below this. Small SMBHs are critical to our understanding of BH formation and growth as well as feedback in the early Universe. We propose to survey all known BHs with mass estimates Mbh < 10^6.2 that have no CXO or XMM observations, but have VLA FIRST radio detections. With modest CXO exposures and new EVLA observations of these 7 sources plus 4 archival sources, we can test the robustness of the plan at low-mass and whether accretion properties scale from stellar BHs thus testing how BH feedback scales with mass and accretion rate.

We examine the possibility that the observed relation between black hole mass and host-galaxy stellar velocity dispersion (the M-σ relation) is biased by an observational selection effect, the difficulty of detecting a black hole whose sphere of influence is smaller than the telescope resolution. In particular, we critically investigate recent claims that the M-σ relation only represents the upper limit to a broad distribution of black hole masses in galaxies of a given velocity dispersion. We find that this hypothesis can be rejected at a high confidence level, at least for the early-type galaxies with relatively high velocity dispersions (median 268 km s<SUP>-1</SUP>) that comprise most of our sample. We also describe a general procedure for incorporating observational selection effects in estimates of the properties of the M-σ relation. Applying this procedure we find results that are consistent with earlier estimates that did not account for selection effects, although with larger error bars. In particular, (1) the width of the M-σ relation is not significantly increased, (2) the slope and normalization of the M-σ relation are not significantly changed, and (3) most or all luminous early-type galaxies contain central black holes at zero redshift. Our results may not apply to late-type or small galaxies, which are not well represented in our sample.

We present axisymmetric, orbit-based models to study the central black hole (BH), stellar mass-to-light ratio (M/L), and dark matter (DM) halo of NGC 4594 (M104, the Sombrero Galaxy). For stellar kinematics, we use published high-resolution kinematics of the central region taken with the Hubble Space Telescope, newly obtained Gemini long-slit spectra of the major axis, and integral field kinematics from the Spectroscopic Areal Unit for Research on Optical Nebulae instrument. At large radii, we use globular cluster kinematics to trace the mass profile and apply extra leverage to recovering the DM halo parameters. We find a BH of mass M <SUB>•</SUB> = (6.6 ± 0.4) × 10<SUP>8</SUP> M <SUB>sun</SUB> and determine the stellar M/L<SUB>I</SUB> = 3.4 ± 0.05 (uncertainties are the 68% confidence band marginalized over the other parameters). Our best-fit DM halo is a cored logarithmic model with asymptotic circular speed V<SUB>c</SUB> = 376 ± 12 km s<SUP>-1</SUP> and core radius r<SUB>c</SUB> = 4.7 ± 0.6 kpc. The fraction of dark to total mass contained within the half-light radius is 0.52. Taking the bulge and disk components into account in our calculation of σ<SUB> e </SUB> puts NGC 4594 squarely on the M-σ relation. We also determine that NGC 4594 lies directly on the M-L relation.

Swift J164449.3+573451 is an exciting transient event, likely powered by the tidal disruption of a star by a massive black hole. The distance to the source, its transient nature, and high internal column density serve to complicate several means of estimating the mass of the black hole. Utilizing newly refined relationships between black hole mass, radio luminosity, and X-ray luminosity, and de-beaming the source flux, a weak constraint on the black hole mass is obtained: log(M <SUB>BH</SUB>/M <SUB>sun</SUB>) = 5.5 ± 1.1 (1σ confidence). The confidence interval is determined from the current intrinsic scatter in the relation, which includes effects from X-ray variability and accretion modes. This mass range is broad, but it includes low values that are consistent with some variability arguments, and it safely excludes high-mass values where it becomes impossible for black holes to disrupt stars. Future refinements in relationships between black hole mass, radio luminosity, and X-ray luminosity will be able to reduce the uncertainty in related mass estimates by a factor of two, making this technique comparable to estimates based on the M-σ relationship. Possible difficulties in placing such events on the fundamental plane, a potential future test of their suitability, and uncertainties in mass stemming from variable X-ray emission are discussed. As near- and longer-term survey efforts such as Pan-STARRS, LSST, LOFAR, the Square Kilometer Array, and eROSITA begin to detect many tidal disruption events, black hole mass estimates from combined X-ray and radio observations may prove to be very pragmatic.

In this paper, we examine whether the properties of central black holes in galactic nuclei correlate with their host dark matter halos. We analyze the entire sample of galaxies where black hole mass, velocity dispersion σ, and asymptotic circular velocity V<SUB>c</SUB> have all been measured. We fit M <SUB>BH</SUB>-σ and M <SUB>BH</SUB>-V<SUB>c</SUB> to a power law, and find that in both relationships the scatter and slope are similar. This model-independent analysis suggests that although the black hole masses are not uniquely determined by dark matter halo mass, when considered for the current sample as a whole, the M <SUB>BH</SUB>-V<SUB>c</SUB> correlation may be as strong (or as weak) as M <SUB>BH</SUB>-σ. Although the data are sparse, there appears to be more scatter in the correlation for both σ and V<SUB>c</SUB> at the low-mass end. This is not unexpected given our current understanding of galaxy and black hole assembly. In fact, there are several compelling reasons that account for this: (1) supermassive black hole (SMBH) formation is likely less efficient in low-mass galaxies with large angular momentum content, (2) SMBH growth is less efficient in low-mass disk galaxies that have not experienced major mergers, and (3) dynamical effects, such as gravitational recoil, increase scatter preferentially at the low-mass end. Therefore, the recent observational claim of the absence of central SMBHs in bulgeless, low-mass galaxies, or deviations from the correlations defined by high-mass black holes in large galaxies today is, in fact, predicated by current models of black hole growth. We show how this arises as a direct consequence of the coupling between dark matter halos and central black holes at the earliest epochs.

We request 2 nights of NIFS + AO time to measure black hole (BH) masses in 4 galaxies selected to provide a vital diagnostic of the distribution of BH mass about the mean Mbh-sigma relation. The galaxies are selected to have the best resolved BH ``spheres of influence" (SOI) predicted by their velocity dispersions. Combined with existing and other proposed measurements this sample will form a statistically complete sample of the best galaxies in the local universe to capture the full distribution of masses. There is concern that observational biases may mean the existing estensive work on BH masses only defines the upper envelope of the BH mass distribution. By focusing on galaxies with predicted large angular SOIs we allow for the greatest range of BH mass at any dispersion to be observed. The observed distribution thereby provides an immediate test of the envelope model.

We report the discovery of a new supernova remnant. Following the detection of an extended source in a Swift/XRT exposure in the Galactic plane, we requested a short 5 ks exposure with Chandra. The Swift observation was obtained on 22 February 2011 (observation 00042184001), and the Chandra ACIS-S observation was obtained on 03 June 2011 (observation 13419).<BR /> <BR /> If characterized with a circle, the center of the remnant could be approximated with the following coordinates: 13:21:50.9, -63:33:50 (J2000), or (l,b) = 306.309034, -0.891719, with a radius of approximately 110 arcseconds.

We report a rebrightening of the newly discovered transient MAXI J0556-332 (ATEL #3102, #3103, #3104, #3106, #3110, #3112, #3116, #3119) in optical through soft-X-ray wavelengths. The source is being <A href="http://www.astro.lsa.umich.edu/~dmaitra/xrb/MAXI_J0556-332/lc.png">monitored regularly</A> in the I-band using the <A href="http://www.astro.yale.edu/smarts/smarts1.3m.html">SMARTS 1.3m telescope</A> in CTIO, and the I-band light curve has been showing a monotonically increasing trend since 55670.9748 (2011 April 19.97, when the I-band magnitude was 18.39 ± 0.15).

We report on the results of a simultaneous monitoring campaign employing eight Chandra X-ray (0.5-10 keV) and six Very Large Array/Extended Very Large Array (8.4 GHz) radio observations of NGC 4051 over seven months. Evidence for compact jets is observed in the 8.4 GHz radio band; this builds on mounting evidence that jet production may be prevalent even in radio-quiet Seyferts. Assuming comparatively negligible local diffuse emission in the nucleus, the results also demonstrate an inverse correlation of L <SUB>radio</SUB> ∝ L <SUP>-0.72±0.04</SUP> <SUB>X-ray </SUB>. If the A configuration is excluded in the case where diffuse emission plays a significant role, the relation is still L_radio ∝ L_{X-ray}^{-0.12 ± 0.05}. Current research linking the mass of supermassive black holes and stellar-mass black holes in the "low/hard" state to X-ray luminosities and radio luminosities suggests a "fundamental plane of accretion onto black holes" that has a positive correlation of L <SUB>radio</SUB> ∝ L <SUP>0.67±0.12</SUP> <SUB>X-ray </SUB>. Our simultaneous results differ from this relation by more than 11σ (6σ excluding the A configuration), indicating that a separate mode of accretion and ejection may operate in this system. A review of the literature shows that the inverse correlation seen in NGC 4051 is seen in three other black hole systems, all of which accrete at near 10% of their Eddington luminosity, perhaps suggesting a distinct mode of disk-jet coupling at high Eddington fractions. We discuss our results in the context of disks and jets in black holes and accretion across the black hole mass scale.

We present the stellar kinematics in the central 2'' of the luminous elliptical galaxy M87 (NGC 4486), using laser adaptive optics to feed the Gemini telescope integral-field spectrograph, Near-infrared Integral Field Spectrograph (NIFS). The velocity dispersion rises to 480 km s<SUP>-1</SUP> at 0farcs2. We combine these data with extensive stellar kinematics out to large radii to derive a black hole mass equal to (6.6 ± 0.4) × 10<SUP>9</SUP> M <SUB>sun</SUB>, using orbit-based axisymmetric models and including only the NIFS data in the central region. Including previously reported ground-based data in the central region drops the uncertainty to 0.25 × 10<SUP>9</SUP> M <SUB>sun</SUB> with no change in the best-fit mass; however, we rely on the values derived from the NIFS-only data in the central region in order to limit systematic differences. The best-fit model shows a significant increase in the tangential velocity anisotropy of stars orbiting in the central region with decreasing radius, similar to that seen at the centers of other core galaxies. The black hole mass is insensitive to the inclusion of a dark halo in the models—the high angular resolution provided by the adaptive optics breaks the degeneracy between black hole mass and stellar mass-to-light ratio. The present black hole mass is in excellent agreement with the Gebhardt & Thomas value, implying that the dark halo must be included when the kinematic influence of the black hole is poorly resolved. This degeneracy implies that the black hole masses of luminous core galaxies, where this effect is important, may need to be re-evaluated. The present value exceeds the prediction of the black hole-dispersion and black hole-luminosity relations, both of which predict about 1 × 10<SUP>9</SUP> M <SUB>sun</SUB> for M87, by close to twice the intrinsic scatter in the relations. The high end of the black hole correlations may be poorly determined at present.

We present results from an adaptive optics study of the central region of M87 using NIFS on Gemini. The kinematics show a dramatic rise in the velocity dispersion with the AO data. The best-fit dynamical model requires the most massive black hole yet measured with spatially-resolved kinematics at 6.6e9 solar masses. The AO data provides a robust measure of the black hole mass since it so well resolves its sphere of influence. This also allows us to probe the stellar orbital structure reliably, where we find a significant increase in tangential orbital anisotropy. Current and future AO data will provide a significant advance for the field.

There is a relation between radio and X-ray luminosities and SMBH mass: the Fundamental Plane. If radio and X-ray are proxies for jet and accretion power, a broad link between them can be inferred. The relation may be used as a proxy for M_BH measurement, but the scatter is big (0.75 dex; sample of 18). Without Seyferts it is tighter than the M-sigma relation (0.25; sample of 8). It is vital to determine if this is from small numbers or a stronger link between accretion and jets at low Eddington rates. We propose to increase the sample with 37-68 ks observations (197 tot.) of 5 SMBHs with dynamical masses ideal for XMM. Together with VLA data, we can increase the total sample by 25% and the LLAGN sample by 50%, advancing our understanding of accretion, jets, and AGN feedback.

Recent MAXI/GSC and Swift/BAT data show a significant increase in X-ray activity.<BR /> <BR /> On 13 July 2010, the Swift/BAT count rate increased from quiescence to 0.0047 ± 0.0012 counts/sec, to 0.0073 ± 0.0010 on 14 July 2010, and to 0.0106 ± 0.0018 on 15 July 2010. This is an average increase of 0.003 counts/sec per day, and the flux has increased by 2.3 since 13 July 2010. The most recent observation is 5.9 sigma above the quiescent level.<BR /> <BR /> Between 12.5 July 2010 and 14.5 July 2010 The MAXI/GSC 2-20 keV count rate also appears to have increased from 0.024 ± 0.010 to 0.048 ± 0.012 counts/sec from, an increase in flux by a factor of 2.<BR /> <BR /> Optical and NIR observations are planned.

Aql X-1 was observed using Swift between 2010 July 16.8965 and 2010 July 16.9083. The source was recently found to start a new outburst as inferred from Swift/BAT and MAXI/GSC monitoring data (ATEL #2742). Preliminary analyses of the XRT (WT mode) "quicklook" data suggests that the 0.6-10 keV spectrum can be well modeled (chi2/dof=565.2/400) by a phenomenological absorbed power law model with column density of (3.4 ± 0.02) E21 per cm2 and photon index 1.65 ± 0.05.

We assess the influence of massive black hole (MBH) ejections from galaxy centres due to gravitational radiation recoil, along the cosmic merger history of the MBH population. We discuss the `danger' of recoil for MBHs as a function of different MBH spin-orbit configurations and of the host halo cosmic bias, and on how that reflects on the occupation fraction of MBHs. We assess ejection probabilities for mergers occurring in a gas-poor environment, in which the MBH binary coalescence is driven by stellar dynamical processes and the spin-orbit configuration is expected to be isotropically distributed. We contrast this case with the `aligned' case. The latter is the more realistic situation for gas-rich, i.e. `wet', mergers, which are expected for high-redshift galaxies. We find that if all haloes at z > 5-7 host an MBH, the probability of the Milky Way (or similar size galaxy) to host an MBH today is less than 50 per cent, unless MBHs form continuously in galaxies. The occupation fraction of MBHs, intimately related to halo bias and MBH formation efficiency, plays a crucial role in increasing the retention fraction. Small haloes, with shallow potential wells and low escape velocities, have a high ejection probability, but the MBH merger rate is very low along their galaxy formation merger hierarchy: MBH formation processes are likely inefficient in such shallow potential wells. Recoils can decrease the overall frequency of MBHs in small galaxies to ~60 per cent, while they have little effect on the frequency of MBHs in large galaxies (at most a 20 per cent effect).

We derive improved versions of the relations between supermassive black hole mass M<SUB>BH</SUB> and host-galaxy bulge velocity dispersion σ and luminosity L (the M<SUB>BH</SUB>-σ and M<SUB>BH</SUB>-L<SUB>bulge</SUB> relations), based on ~ 50 M<SUB>BH</SUB> measurements and ~ 20 upper limits. Particular attention is paid to recovery of the intrinsic scatter (ɛ<SUB>0</SUB>) in both relations. We find the scatter to be significantly larger than estimated in most previous studies. The large scatter requires revision of the local black hole mass function, and it implies that there may be substantial selection bias in studies of the evolution of the M<SUB>BH</SUB>-σ and M<SUB>BH</SUB>-L<SUB>bulge</SUB> relations. When only considering ellipticals, the scatter decreases. These results appear to be insensitive to a wide range of assumptions about the measurement errors and the distribution of intrinsic scatter. We also investigate the effects on the fits of culling the sample according to the resolution of the black hole's sphere of influence.

Black hole accretion and jet production are areas of intensive study in astrophysics. Recent work has found a relation between radio luminosity, X-ray luminosity, and black hole mass. With the assumption that radio and X-ray luminosity are suitable proxies for jet power and accretion power, respectively, a broad fundamental connection between accretion and jet production is implied. In an effort to refine these links and enhance their power, we have explored the above relations exclusively among black holes with direct, dynamical mass-measurements. This approach not only eliminates systematic errors incurred through the use of secondary mass measurements, but also effectively restricts the range of distances considered to a volume-limited sample. Further, we have exclusively used archival data from the Chandra X-ray Observatory to best isolate nuclear sources. We find L<SUB>r</SUB> = (4.59 +/- 0.23) + (0.80 +/- 0.26) M<SUB>BH</SUB> + (0.67 +/- 0.12) L<SUB>x</SUB>, in broad agreement with prior efforts. Owing to the nature of our sample, the plane can be turned into an effective mass predictor. When the full sample is considered, masses are predicted less accurately than with the well-known M-sigma relation. If obscured AGN are excluded, the plane is potentially a better predictor than other scaling measures.

Shortly after a galaxy merger, the supermassive black holes from each galaxy are thought to form a binary at the center of the merger remnant. The binary orbit shrinks via three-body scattering of stars until the black holes are close enough to strongly emit gravitational radiation and merge. Since a substantial fraction of the scattered stars are ejected with enough energy to escape the host galaxy, three-body encounters with a supermassive binary black hole are a viable mechanism to generate hypervelocity stars. We investigate the 3-d spatial and kinematic distribution of the stars that are scattered by interacting with a supermassive binary black hole. We simulate each three body encounter explicitly, including gravitational radiation, until the stellar interloper has either been ejected or has merged with a black hole. Then, we evolve the positions and velocities of the scattered stars self-consistently within an N-body galactic model. By mapping the motion of these scattered stars as they traverse the galactic potential, we can characterize their distribution and how it evolves with time. We discuss how the anisotropic distribution of the scattered stars could allow us to determine characteristics of the black hole binary, as well as aid in the search for hypervelocity stars.

We report on recently derived improved versions of the relations between supermassive black hole mass (M_BH) and host-galaxy bulge velocity dispersion (sigma) and luminosity (L) (the M-sigma and M-L relations), based on ~50 M_BH measurements and ~20 upper limits. Particular attention is paid to recovery of the intrinsic scatter (epsilon_0) in both relations. The scatter was found to be significantly larger than estimated in most previous studies. The large scatter requires revision of the local black hole mass function, and it implies that there may be substantial selection bias in studies of the evolution of the M-sigma and M-L relations. When only considering ellipticals, the scatter appears to decrease. These results appear to be insensitive to a wide range of assumptions about the measurement errors and the distribution of intrinsic scatter. We also report on the effects on the fits of culling the sample according to the resolution of the black hole's sphere of influence.

Black hole accretion and jet production are areas of intensive study in astrophysics. Recent work has found a relation between radio luminosity, X-ray luminosity, and black hole mass. With the assumption that radio and X-ray luminosities are suitable proxies for jet power and accretion power, respectively, a broad fundamental connection between accretion and jet production is implied. In an effort to refine these links and enhance their power, we have explored the above relations exclusively among black holes with direct, dynamical mass-measurements. This approach not only eliminates systematic errors incurred through the use of secondary mass measurements, but also effectively restricts the range of distances considered to a volume-limited sample. Further, we have exclusively used archival data from the Chandra X-ray Observatory to best isolate nuclear sources. We find log L<SUB>R</SUB> = (4.80 ± 0.24) + (0.78 ± 0.27)log M <SUB>BH</SUB> + (0.67 ± 0.12)log L<SUB>X</SUB> , in broad agreement with prior efforts. Owing to the nature of our sample, the plane can be turned into an effective mass predictor. When the full sample is considered, masses are predicted less accurately than with the well-known M-σ relation. If obscured active galactic nuclei are excluded, the plane is potentially a better predictor than other scaling measures.

Galaxies with dynamically-measured central BH masses allow us to understand BH accretion, jets, and interactions between BHs and host galaxies with a clarity not possible in random surveys. By measuring true Eddington fractions, we can calculate the energy in radiation vs mechanical jet energy and the efficacy of BHs in heating nuclear regions and affecting star formation. Remarkably, 1/3 of SMBHs making up the M-sigma relation have been poorly observed or totally unobserved with Chandra. We propose a survey of 15 M-sigma galaxies to complete the sample of reliable M-sigma SMBHs. For each galaxy we propose to obtain 30-60 ks exposures and an hour-long VLA observation. This survey will test and extend the fundamental plane of BH activity and facilitate studies of the origin of M-sigma.

We derive improved versions of the relations between supermassive black hole mass (M <SUB>BH</SUB>) and host-galaxy bulge velocity dispersion (σ) and luminosity (L; the M-σ and M-L relations), based on 49 M <SUB>BH</SUB> measurements and 19 upper limits. Particular attention is paid to recovery of the intrinsic scatter (epsilon<SUB>0</SUB>) in both relations. We find log(M <SUB>BH</SUB>/M <SUB>sun</SUB>) = α + βlog(σ/200 km s<SUP>-1</SUP>) with (α, β, epsilon<SUB>0</SUB>) = (8.12 ± 0.08, 4.24 ± 0.41, 0.44 ± 0.06) for all galaxies and (α, β, epsilon<SUB>0</SUB>) = (8.23 ± 0.08, 3.96 ± 0.42, 0.31 ± 0.06) for ellipticals. The results for ellipticals are consistent with previous studies, but the intrinsic scatter recovered for spirals is significantly larger. The scatter inferred reinforces the need for its consideration when calculating local black hole mass function based on the M-σ relation, and further implies that there may be substantial selection bias in studies of the evolution of the M-σ relation. We estimate the M-L relationship as log(M <SUB>BH</SUB>/M <SUB>sun</SUB>) = α + βlog(L<SUB>V</SUB> /10<SUP>11</SUP> L <SUB>sun,V </SUB>) of (α, β, epsilon<SUB>0</SUB>) = (8.95 ± 0.11, 1.11 ± 0.18, 0.38 ± 0.09); using only early-type galaxies. These results appear to be insensitive to a wide range of assumptions about the measurement errors and the distribution of intrinsic scatter. We show that culling the sample according to the resolution of the black hole's sphere of influence biases the relations to larger mean masses, larger slopes, and incorrect intrinsic residuals.

We report five new measurements of central black hole masses based on Space Telescope Imaging Spectrograph and Wide Field Planetary Camera 2 observations with the Hubble Space Telescope (HST) and on axisymmetric, three-integral, Schwarzschild orbit-library kinematic models. We selected a sample of galaxies within a narrow range in velocity dispersion that cover a range of galaxy parameters (including Hubble type and core/power-law surface density profile) where we expected to be able to resolve the galaxy's sphere of influence based on the predicted value of the black hole mass from the M-σ relation. We find masses for the following galaxies: NGC 3585, M <SUB>BH</SUB> = 3.4<SUP>+1.5</SUP> <SUB>-0.6</SUB> × 10<SUP>8</SUP> M <SUB>sun</SUB>; NGC 3607, M <SUB>BH</SUB> = 1.2<SUP>+0.4</SUP> <SUB>-0.4</SUB> × 10<SUP>8</SUP> M <SUB>sun</SUB>; NGC 4026, M <SUB>BH</SUB> = 2.1<SUP>+0.7</SUP> <SUB>-0.4</SUB> × 10<SUP>8</SUP> M <SUB>sun</SUB>; and NGC 5576, M <SUB>BH</SUB> = 1.8<SUP>+0.3</SUP> <SUB>-0.4</SUB> × 10<SUP>8</SUP> M <SUB>sun</SUB>, all significantly excluding M <SUB>BH</SUB> = 0. For NGC 3945, M <SUB>BH</SUB> = 9<SUP>+17</SUP> <SUB>-21</SUB> × 10<SUP>6</SUP> M <SUB>sun</SUB>, which is significantly below predictions from M-σ and M-L relations and consistent with M <SUB>BH</SUB> = 0, though the presence of a double bar in this galaxy may present problems for our axisymmetric code. <P />Based on observations made with the Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with GO proposals 5999, 6587, 6633, 7468, and 9107.

During the inspiral and merger of a binary black hole, gravitational radiation is emitted anisotropically due to asymmetries in the merger configuration. This anisotropic radiation leads to a gravitational wave kick, or recoil velocity, as large as ~4000 km s<SUP>-1</SUP>. We investigate the effect gravitational recoil has on the retention of intermediate-mass black holes (IMBHs) within the population of Galactic globular clusters by simulating the response of IMBHs to black hole mergers. Assuming that our current understanding of IMBH formation is correct and yields an IMBH seed in every globular cluster, we find a significant problem in retaining low-mass IMBHs (lesssim1000 M<SUB>⊙</SUB>) in the typical merger-rich globular cluster environment. Given a uniform black hole spin distribution and orientation and a stellar-mass black hole mass function generated in a low-metallicity system, we find that only three of the Milky Way globular clusters can retain an IMBH with an initial mass of 200 M<SUB>⊙</SUB>. Even if IMBHs have an initial mass of 1000 M<SUB>⊙</SUB>, only 60 would remain within Milky Way globular clusters, and each would reside only in the most massive clusters. Our calculations show that if there are black holes of mass M > 50 M<SUB>⊙</SUB> in a cluster, repeated IMBH-black hole encounters will eventually eject a M = 1000 M<SUB>⊙</SUB> IMBH with greater than 30% probability. As a consequence, a large population of rogue black holes may exist in our Milky Way halo. We briefly discuss the dynamical implications of this process and its possible connection to ultraluminous X-ray sources (ULXs).

We investigate the distribution of massive black holes (MBHs) in the Virgo cluster. Observations suggest that active galactic nuclei activity is widespread in massive galaxies (M<SUB>*</SUB> >~ 10<SUP>10</SUP>M<SUB>solar</SUB>), while at lower galaxy masses star clusters are more abundant, which might imply a limited presence of central black holes in these galaxy-mass regimes. We explore if this possible threshold in MBH hosting is linked to nature, nurture or a mixture of both. The nature scenario arises naturally in hierarchical cosmologies, as MBH formation mechanisms typically are efficient in biased systems, which would later evolve into massive galaxies. Nurture, in the guise of MBH ejections following MBH mergers, provides an additional mechanism that is more effective for low mass, satellite galaxies. The combination of inefficient formation, and lower retention of MBHs, leads to the natural explanation of the distribution of compact massive objects in Virgo galaxies. If MBHs arrive to the correlation with the host mass and velocity dispersion during merger-triggered accretion episodes, sustained tidal stripping of the host galaxies creates a population of MBHs which lie above the expected scaling between the holes and their host mass, suggesting a possible environmental dependence.

During the inspiral and merger of a binary black hole, gravitational radiation is emitted anisotropically due to asymmetries in the merger configuration. This anisotropic radiation leads to a gravitational wave kick, or recoil velocity, as large as 4000 km/sec. We investigate the effect gravitational recoil has on the retention of intermediate mass black holes (IMBH) within Galactic globular clusters. Assuming that our current understanding of IMBH-formation is correct and yields an IMBH-seed in every globular cluster, we find a significant problem retaining low mass IMBHs in the typical merger-rich globular cluster environment. Given a uniform black hole spin distribution and orientation and a Kroupa IMF, we find that at most 3 percent of the globular clusters can retain an IMBH larger than 1000 solar masses today. For a population of black holes that better approximates mass loss from winds and supernovae, we find that 16 percent of globulars can retain an IMBH larger than 1000 solar masses. Our calculations show that if there are black holes larger than 60 solar masses in a cluster, repeated IMBH-BH encounters will eventually eject a 1000 solar mass IMBH with greater than 30 percent probability. As a consequence, a large population of rogue black holes may exist in our Milky Way halo. We discuss the dynamical implications of this subpopulation, and its possible connection to ultraluminous X-ray sources (ULXs).

We present the latest analysis of the relationship between nuclear black hole mass and properties of the host galaxy or bulge, notably stellar velocity dispersion. This analysis includes six new measurements of black hole masses based on observations with HST using STIS and WFPC2 as well as the most recent results from the literature for a total of about 50 dynamical black hole mass measurements. We also include in our analysis, for the first time, 15 measured upper limits on black hole mass. <P />Studies of supermassive black holes in galaxy centers have led to the discoveries that most or all hot galaxies contain massive dark objects at their centers, presumably black holes; and that there is a remarkably tight correlation between the black-hole mass and the luminosity-weighted velocity dispersion of the hot component of the galaxy. This M-sigma relationship suggests a strong link between black-hole formation, AGN activity, and galaxy formation, and once it is understood, this link should advance our understanding of all three processes. In this work we (1) present the most current fit to the M-sigma relation; (2) measure the scatter in the relation, which previous studies claim to be consistent with zero scatter; and (3) investigate the role of possible second parameters in predicting black hole mass, that is a fundamental plane relationship.

Recent numerical relativistic simulations have found that recoil from gravitational wave emission of merging black holes can produce kicks up to 1000 km/s. Because intermediate-mass black holes (IMBHs) are thought to form in dense stellar clusters, their ejection from the cluster becomes a real possibility. In this talk we present results on the retention probability of IMBHs as they interact with the host cluster's stellar-mass black hole population. We consider the ramifications of gravitational wave recoil and potential for further growth as the IMBHs merge with stellar mass black holes. We consider IMBHs that are the evolution of Population III stars, core-collapse runaway merger remnants (including multiples), and those built up from mergers of stellar-mass black holes.

We present results of numerical simulations of sequences of binary-single scattering events of black holes in dense stellar environments. The simulations cover a wide range of mass ratios from equal mass objects to 1000:10:10 [Special characters omitted.] and compare purely Newtonian simulations with a relativistic endpoint, simulations in which Newtonian encounters are interspersed with gravitational wave emission from the binary, and simulations that include the effects of gravitational radiation reaction by using equations of motion that include the 2.5-order post-Newtonian force terms, which are the leading-order terms of energy loss from gravitational waves. In all cases, the sequence is terminated when the binary's merger time due to gravitational radiation is less than the arrival time of the next interloper. We also examine the role of gravitational waves during an encounter and show that close approach cross-sections for three 1 [Special characters omitted.] objects are unchanged from the purely Newtonian dynamics except for close approaches smaller than 10-5 times the initial semimajor axis of the binary. We also present cross-sections for mergers resulting from gravitational radiation during three-body encounters for a range of binary semimajor axes and mass ratios including those of interest for intermediate-mass black holes (IMBHs). We find that black hole binaries typically merge with a very high eccentricity- --extremely high when gravitational waves are included during the encounter such that when the gravitational waves are detectable by LISA, most of the binaries will have eccentricities e > 0.9 though all will have circularized by the time they are detectable by LIGO. We also investigate the implications for the formation and growth of IMBHs and find that the inclusion of gravitational waves during the encounter results in roughly half as many black holes ejected from the host cluster for each black hole accreted onto the growing IMBH. The simulations show that the Miller & Hamilton (2002b) model of IMBH formation is a viable method if it is modified to start with a larger seed mass.

We present numerical three-body experiments that include the effects of gravitational radiation reaction by using equations of motion that include the 2.5-order post-Newtonian force terms, which are the leading-order terms of energy loss from gravitational waves. We simulate binary-single interactions and show that close-approach cross sections for three 1 M<SUB>solar</SUB> objects are unchanged from the purely Newtonian dynamics except for close approaches smaller than 10<SUP>-5</SUP> times the initial semimajor axis of the binary. We also present cross sections for mergers resulting from gravitational radiation during three-body encounters for a range of binary semimajor axes and mass ratios including those of interest for intermediate-mass black holes (IMBHs). Building on previous work, we simulate sequences of high-mass-ratio three-body encounters that include the effects of gravitational radiation. The simulations show that the binaries merge with extremely high eccentricity such that when the gravitational waves are detectable by LISA, most of the binaries will have eccentricities e>0.9, although all will have circularized by the time they are detectable by LIGO. We also investigate the implications for the formation and growth of IMBHs and find that the inclusion of gravitational waves during the encounter results in roughly half as many black holes ejected from the host cluster for each black hole accreted onto the growing IMBH.

We present numerical three-body experiments that include the effects of gravitational radiation reaction by using equations of motion that include the 2.5-order post-Newtonian force terms, which are the leading order terms of energy loss from gravitational waves. Building on previous work, we simulate sequences of high-mass-ratio three-body encounters as they would occur in a dense stellar system. The simulations show that the binaries merge with extremely high eccentricity such that when the gravitational waves are detectable by LISA, most of the binaries will have eccentricities e > 0.9 though all will have circularized by the time they are detectable by LIGO. We also investigate the implications for the formation and growth of intermediate-mass black holes (IMBHs) and find that the inclusion of gravitational waves during the encounter results in roughly half as many black holes ejected from the host cluster for each black hole accreted onto the growing IMBH.

We present results of numerical simulations of sequences of binary-single scattering events of black holes in dense stellar environments. The simulations cover a wide range of mass ratios from equal mass objects to 1000:10:10 M<SUB>solar</SUB> and compare purely Newtonian simulations to simulations in which Newtonian encounters are interspersed with gravitational wave emission from the binary. In both cases, the sequence is terminated when the binary's merger time due to gravitational radiation is less than the arrival time of the next interloper. We find that black hole binaries typically merge with a very high eccentricity (0.93<=e<=0.95 pure Newtonian; 0.85<=e<=0.90 with gravitational wave emission) and that adding gravitational wave emission decreases the time to harden a binary until merger by ~30%-40%. We discuss the implications of this work for the formation of intermediate-mass black holes and gravitational wave detection.

Evidence has been mounting for the existence of black holes with masses from 10^2 to 10^4 M_Solar associated with stellar clusters. Such intermediate-mass black holes (IMBHs) will encounter other black holes in the dense cores of these clusters. The binaries produced in these interactions will be perturbed by other objects as well thus changing the orbital characteristics of the binaries. These binaries and their subsequent mergers due to gravitational radiation are important sources of gravitational waves. We present the results of numerical simulations of high mass ratio encounters, which help clarify the interactions of intermediate-mass black holes in globular clusters and help determine what types of detectable gravitational wave signatures are likely.

Recent x-ray observations suggest that a number of galaxies may harbor black holes with masses between 10<SUP>2</SUP> and 10<SUP>3-4</SUP> M<SUB>Sun</SUB>. These intermediate-mass black holes may require a formation mechanism different from those of stellar-mass black holes and supermassive black holes. Several models have been proposed to account for their origin, one of which proposes that stellar-mass black holes in dense globular clusters may grow to the required masses through mergers. We investigate this scenario numerically, by examining the role of interactions between binary black holes and single black holes. We present results of numerical simulations of these encounters and discuss their implications for the formation of intermediate-mass black holes and for their detectability with gravitational wave detectors such as LISA and LIGO-II.

We present subarcsecond thermal infrared imaging of HD 98800, a young quadruple system composed of a pair of low-mass spectroscopic binaries separated by 0.8" (38 AU), each with a K-dwarf primary. Images at wavelengths ranging from 5 to 24.5 μm show unequivocally that the optically fainter binary, HD 98800B, is the sole source of a comparatively large infrared excess on which a silicate emission feature is superposed. The excess is detected only at wavelengths of 7.9 μm and longer, peaks at 25 μm, and has a best-fit blackbody temperature of 150 K, indicating that most of the dust lies at distances greater than the orbital separation of the spectroscopic binary. We estimate the radial extent of the dust with a disk model that approximates radiation from the spectroscopic binary as a single source of equivalent luminosity. Given the data, the most likely values of disk properties in the ranges considered are R<SUB>in</SUB>=5.0+/-2.5 AU, ΔR=13+/-8 AU, λ<SUB>0</SUB>=2<SUP>+4</SUP><SUB>-1.5</SUB> μm, γ=0+/-2.5, and σ<SUB>total</SUB>=16+/-3 AU<SUP>2</SUP>, where R<SUB>in</SUB> is the inner radius, ΔR is the radial extent of the disk, λ<SUB>0</SUB> is the effective grain size, γ is the radial power-law exponent of the optical depth τ, and σ<SUB>total</SUB> is the total cross section of the grains. The range of implied disk masses is 0.001-0.1 times that of the Moon. These results show that, for a wide range of possible disk properties, a circumbinary disk is far more likely than a narrow ring.

We present sub-arcsecond thermal infrared imaging of HD 98800, a young quadruple system composed of a pair of low-mass spectroscopic binaries separated by 0.8'', each with a K-dwarf primary. Images at wavelengths ranging from 5 to 24.5 microns show unequivocally that the optical secondary, HD 98800B, is the sole source of a comparatively large infrared excess upon which a silicate emission feature is superposed. The excess is detected only at wavelengths of 7.9 microns and longer, peaks at 25 microns, and has a best-fit black-body temperature of 146 K. With the assumption that the dust is in radiative equilibrium with the central stars, these characteristics require its location to be in a configuration that is circumbinary to the spectroscopic pair. A simple black-body fit underpredicts emission in the region of the broad silicate feature, however, and the feature itself requires a dust component with temperatures higher than 146 K by at least a factor of two. Further, the spectral slope at sub-millimeter wavelengths is flatter than expected for a collision-induced size-distribution of grains, suggesting a range of temperatures present at longer wavelengths. These facts suggest that the circumbinary dust is not confined to a narrow ring but is wide enough to exhibit a range of temperatures.

We present aperture synthesis mapping of a circumstellar disk around the high-mass protostellar source, L1206A. A contour map at 110 GHz reveals dust emission with peak flux density 32.5 +/-3 mJy in a circular 2'' beam, and integrated intensity 62 +/-6 mJy. The emission is elongated perpendicular to a bipolar reflection nebula with a nominal FWHM diameter of 2.3+/-0.05'' (deconvolved), corresponding to 2300 AU at the 1 kpc distance estimated for the Lynds 1206 cloud. Visibility amplitudes are well-matched by those predicted from a model of dust radiation arising from a circumstellar disk. Preliminary model-fitting suggests the disk has outer radius 4000 AU and mass greater than 0.3M_sun.