Growth of supermassive black holes, galaxy mergers and supermassive binary black holes

TL;DR

This paper reviews the role of galaxy mergers and supermassive binary black holes in cosmic structure formation, emphasizing their importance for black hole growth, gravitational wave sources, and future observational prospects.

Contribution

It synthesizes current understanding of galaxy mergers, SMBH growth, and gravitational wave implications, highlighting future GW astronomy's potential to advance the field.

Findings

Galaxy mergers drive SMBH growth and quasar activity.

Coalescing SMBH binaries are key gravitational wave sources.

Future GW observations will enhance understanding of black hole evolution.

Abstract

The study of galaxy mergers and supermassive binary black holes (SMBBHs) is central to our understanding of the galaxy and black hole assembly and (co-)evolution at the epoch of structure formation and throughout cosmic history. Galaxy mergers are the sites of major accretion episodes, they power quasars, grow supermassive black holes (SMBHs), and drive SMBH-host scaling relations. The coalescing SMBBHs at their centers are the loudest sources of gravitational waves (GWs) in the universe, and the subsequent GW recoil has a variety of potential astrophysical implications which are still under exploration. Future GW astronomy will open a completely new window on structure formation and galaxy mergers, including the direct detection of coalescing SMBBHs, high-precision measurements of their masses and spins, and constraints on BH formation and evolution in the high-redshift universe.