Collaborative Research: Mergers of Massive Black Holes at the Centers of Galaxies

Columbia University, New York NY

Investigators

Abstract

The investigators will explore how black holes (BHs) grow and shine over long timescales. Most galaxies have enormous black holes at their centers, surrounded by stars, planets, dust, and ionized gas. Stars formed by this material can also feed the black hole. These black holes have masses that are up to billions of times the mass of the Sun. Galaxies repeatedly merge with other galaxies during their lifetimes. Thus, super massive black hole pairs form frequently. These pairs of black holes make ripples in space and time called gravitational waves. As such, they are prime targets for gravitational wave detectors. Gravitational wave simulations provide a new way to explore the Universe. The investigators' computer simulations will help determine how black hole binaries interact with surrounding material. The investigators' simulations will help astronomers detect merging black holes and understand the regions surrounding the black holes. The investigators will train students and develop new numerical codes that can be used for a wide variety of science and engineering applications. The investigators will numerically simulate the long-term merger dynamics of supermassive black hole binaries (SMBHB) with disks of gas, planets, and stars surrounding the black holes. The investigators will model, in detail, the hydrodynamical reaction of the disk to the orbital motion of the SMBHBs as well as the back-reaction of the disk on this orbital motion. These theorists seek to answer several questions important for understanding astronomical observations. They will model the time it takes for the two black holes to merge in the presence of different types of gas disks. Observationally, it is important to estimate how bright the region surrounding the SMBHB will be during merger. The results will be applied to interpret observations of the stochastic gravitational wave background, periodicities in quasar light-curves in large time-domain surveys, and gravitational wave strength of stellar-mass BHs.