Energy input from quasars regulates the growth and activity of black holes and their host galaxies

Abstract

In the early Universe, while galaxies were still forming, black holes as massive as a billion solar masses powered quasars. Supermassive black holes are found at the centers of most galaxies today 1,2,3 , where their masses are related to the velocity dispersions of stars in their host galaxies and hence to the mass of the central bulge of the galaxy 4,5 . This suggests a link between the growth of the black holes and the host galaxies 6,7,8,9 , which has indeed been assumed for a number of years. But the origin of the observed relation between black hole mass and stellar velocity dispersion, and its connection with the evolution of galaxies have remained unclear. Here we report hydrodynamical simulations that simultaneously follow star formation and the growth of black holes during galaxy-galaxy collisions. We find that in addition to generating a burst of star formation 10 , a merger leads to strong inflows that feed gas to the supermassive black hole and thereby power the quasar. The energy released by the quasar expels enough gas to quench both star formation and further black hole growth. This determines the lifetime of the quasar phase (approaching 100 million years) and explains the relationship between the black hole mass and the stellar velocity

Evidence of ongoing AGN-driven feedback in a quiescent post-starburst E+A galaxy

“…Various processes can quench the massive, ongoing, SF in such systems (negative feedback). Common sources of negative feedback are supernova-(SN) and AGN-driven winds, which can heat the gas via shocks, and photoionize it (Heckman, Armus & Miley 1990;Di Matteo, Springel & Hernquist 2005;Springel et al 2005;Ciotti, Ostriker & Proga 2010;Feruglio et al 2010;Cicone et al 2014). Feedback can also affect the gas supply to the vicinity of the central SMBH.…”

Did galaxy assembly and supermassive black-hole growth go hand-in-hand?

“…Recent state-of-the-art hydrodynamical models (di Matteo et al 2005;Springel et al 2005ab;Hopkins et al 2005) suggest that during (major) mergers, the BH accretion rate peaks considerably after the merger started, and after the star-formation rate (SFR) has peaked. Their models suggest that, for massive galaxies, a tadpole stage is seen typically about 0.7 Gyr after the merger started, but ∼1 Gyr before the SMBH accretes most of its mass, which is when the galaxy displays strong visible AGN activity.…”

AGN and Host Galaxies in the COSMOS Survey

“…A paradigm shift occurred when it became clear that all galaxies harbor a supermassive black hole, with a mass scaling according to the population of old stars, and a duty cycle of activity where the nucleus was mostly quiescent (Soltan 1982, Magorrian et al 1998. Alongside that was the realization that active nuclei affect their host galaxies just as profoundly as the immediate environment affects the behavior of the nuclear region (Di Matteo, Springel & Hernquist 2005). The co-evolution of supermassive black holes and galaxies has become a burgeoning research area.…”