The Interplay Between Massive Black Holes and their Hosts during Galaxy Mergers

[Original PI was Marta Volonteri.]

This project is a comprehensive theoretical study that will provide a picture of how massive black holes (MBHs) in galaxy centers evolved from early cosmic times to the present day. In the first two parts of the three-part study, coupled gravitational N-body and smooth-particle hydrodynamics simulations will be used by the Principal Investigator and a graduate student to study the growth of MBHs in mergers of galaxies. The first part is aimed at understanding when MBHs form bound pairs following galaxy mergers, and when they light up as single or double active galactic nuclei (AGN). Simulations will explore a range of mass ratios and galaxy morphologies. The second part addresses the dynamical, thermodynamic, and accretion evolution of a MBH pair in a merger remnant. The MBH evolution will be simulated at high resolution, self-consistently following the interplay between accretion and dynamics. The third part of the project will use the simulation results to calculate the evolution of MBH populations along cosmic time, predicting how many MBH mergers are expected in the Universe, and how often AGN occur in merging galaxies. The predicted observables will be: (i) frequency of MBHs in galaxies as a function of galaxy mass and cosmic time, (ii) statistics on double AGNs, and on the luminosity functions of AGN at different redshifts and wavelengths, and (iii) potentially detectable gravitational wave event rates from mergers. The proposed research will constrain the dynamics and mass growth of MBHs during mergers and their frequency in galaxies, key information for models of galaxy evolution. The project will contribute to training the next generation of scientists through support of a doctoral student. In an outreach component, undergraduate students will develop critical thinking by designing a museum exhibit dealing with common misconceptions on black holes.