Supermassive black holes, once thought to be theoretical novelties, are now considered to play a major role in many astrophysical phenomena including galaxy evolution. Now that we live in the era of gravitational wave observations, it is interesting to look forward to a time when we can detect gravitational waves from supermassive black hole coalescence. A major question remains: Do supermassive black holes merge?  I will review the case for supermassive black holes as active players in the universe, focusing on the black hole outflows. Then I will concentrate on my group’s recent work searching for dual and binary AGNs along with recent developments: (1) closer inspection of time-domain-identified binary candidates; (2) a Bayesian framework for determining duality in a Chandra observation; and (3) spectroscopic and time-domain identification of low-mass-ratio binary AGN.

Supermassive black holes, once thought to be theoretical novelties, are now considered to play a major role in many astrophysical phenomena including galaxy evolution. Now that we live in the era of gravitational wave observations, it is interesting to look forward to a time when we can detect gravitational waves from supermassive black hole coalescence. A major question remains: Do supermassive black holes merge?  I will review the case for supermassive black holes as active players in the universe, focusing on black hole outflows. Then I will concentrate on my group’s recent work searching for dual and binary supermassive black holes along with recent developments: (1) closer inspection of time-domain-identified binary candidates; (2) a Bayesian framework for determining duality in a Chandra observation; and (3) spectroscopic and time-domain identification of low-mass-ratio binaries.

Supermassive black holes, once thought to be theoretical novelties, are now considered to play a major role in many astrophysical phenomena including galaxy evolution. Now that we live in the era of gravitational wave observations, it is interesting to look forward to a time when we can detect gravitational waves from supermassive black hole coalescence. A major question remains: Do supermassive black holes merge?  I will review the case for supermassive black holes as active players in the universe, focusing on the black hole outflows. Then I will concentrate on my group’s recent work searching for dual and binary supermassive black holes along with recent developments: (1) closer inspection of time-domain-identified binary candidates; (2) a Bayesian framework for determining duality in a Chandra observation; and (3) spectroscopic and time-domain identification of low-mass-ratio binaries.

Supermassive black holes, once thought to be theoretical novelties, are now considered to play a major role in many astrophysical phenomena including galaxy evolution. Now that we live in the era of gravitational wave observations, it is interesting to look forward to a time when we can detect gravitational waves from supermassive black hole coalescence. A major question remains: Do supermassive black holes merge?  I will review the case for supermassive black holes as active players in the universe, focusing on the black hole outflows. Then I will focus on my recent work searching for dual and binary AGNs along with recent developments: (1) closer inspection of time-domain-identified binary candidates; (2) a Bayesian framework for determining duality in a Chandra observation; and (3) spectroscopic and time-domain identification of low-mass-ratio binary AGN.

Supermassive black holes, once thought to be theoretical novelties, are now considered to play a major role in many astrophysical phenomena including galaxy evolution. Now that we live in the era of gravitational wave observations, it is interesting to look forward to a time when we can detect gravitational waves from supermassive black hole coalescence. A major question remains: Do supermassive black holes merge?  I will review the case for supermassive black holes role in the universe, focusing on the black hole mass scaling relations. Then I will focus on my recent work searching for dual and binary AGNs along with recent developments: (1) closer inspection of time-domain-identified binary candidates; (2) a Bayesian framework for determining duality in a Chandra observation; and (3) spectroscopic and time-domain identification of low-mass-ratio binary AGN.

Supermassive black holes, once thought to be theoretical novelties, are now considered to play a major role in many astrophysical phenomena including galaxy evolution. Now that we live in the era of gravitational wave observations, it is interesting to look forward to a time when we can detect gravitational waves from supermassive black hole coalescence. A major question remains: Do supermassive black holes merge?  I will review the case for supermassive black holes role in the universe, focusing on the black hole mass scaling relations. Then I will introduce a new, empirical scaling relation that can be used for black hole mass estimation. Finally I will discuss the prospects and pitfalls of searching for dual and binary AGNs along with recent devlopments.  These include (1) closer inspection of time-domain-identified binary candidates; (2) a Bayesian framework for determining duality in a Chandra observation; and (3) spectroscopic and time-domain identification of low-mass-ratio binary AGN.

Supermassive black holes are some of the most fascinating energetic objects in the Universe, and they play a key role in what we can see across cosmic time and a large range of critical astrophysical phenomena.  Despite their importance, much is unknown about their basic physics including how they were formed, how they grow, how they appear in different wavelengths, and what kind of galaxies they live in.  The answers to many of these basic questions are within reach.  I will review my recent, current, and future research plans to find their solutions.

Stellar dynamical measurements of black hole masses have become the de facto standard method. I will give a brief review of how this measurement method works, along with arguments for its overall reliability and caveats. Then I will turn my attention to the case of the black hole in M87. The black hole is undeniably large — billions of solar masses — but has a stellar dynamical mass measurement in disagreement with gas dynamical mass measurements at about the 2 sigma level. I will discuss potential systematic uncertainties in both measurements and avenues to reconciling the discrepancy.

It has been over a decade since the discovery that the mass of a central black hole scales with the properties of its host galaxy. Because of these remarkable scaling relations, the idea that galaxies and black holes coevolve through some sort of self-regulated feedback has come to dominate scientific discussion. But do we really understand what the scaling relations are telling us? I will review state of the field and present recent developments from the observational perspective of the black hole scaling relations, including our discovery of a 1.7e10 solar mass black hole in a galaxy with stellar mass only 1.2e11 solar masses, discussing how well coevolution models and their alternatives can handle this.

In addition to coevolution, the scaling relations in the local universe inform the study of formation of black hole seeds, black hole density functions across cosmic time, and the disputed claims of evolution of the scaling relations with redshift. I will discuss my new empirical-observational tool for using X-ray and radio measurements to measure black  hole masses and understand the physics of accretion and outflow.

The history of searches for binary supermassive black holes is riddled with false positives and controversial findings. I will present recent and in-progress theoretical calculations to describe the electromagnetic signature of an accreting supermassive black hole with a small companion. This will lead into future observational searches for the tightest binary supermassive black holes.

I will conclude by exploring what important, observational and theoretical questions still need to be answered.

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It has been over a decade since the discovery that the mass of a central black hole scales with the
properties of its host galaxy. Because of these remarkable scaling relations, the idea that galaxies
and black holes coevolve through some sort of self-regulated feedback has come to dominate scientific
discussion. But do we really understand what the scaling relations are telling us? I will review state
of the field and present recent developments from the observational perspective of the black hole
scaling relations, including our rediscovery of a 1.7e10 solar mass black hole in a galaxy with stellar
mass only 1.2e11 solar masses, discussing how well coevolution models and their alternatives can handle
this.
In addition to coevolution, the scaling relations in the local universe inform the study of formation of
black hole seeds, black hole density functions across cosmic time, and the disputed claims of evolution of
the scaling relations with redshift. I will discuss my theoretical works in these areas as well as my
work on a new tool for using X-ray and radio measurements to measure black hole masses. I will conclude by exploring what important, observational and theoretical questions still need to be answered.

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.