Tuesday

We present a simple model for the co-evolution of the AGN and galaxy populations. This model builds on ideas from an earlier model presented in Caplar et al (2015). The new feature is that black hole growth is now associated with the ending of star-formation in galaxies ("quenching") instead of the gradual build up of stellar populations over long periods of time. The model enables us to self-consistently and analytically link (a) the evolution of the stellar mass function of star-forming galaxies, (b) the evolution of the luminosity function of AGN, (c) the evolution of the star mass/black hole mass relation for both active and passive populations, and (d) the evolving ratio of the overall star-formation rate density (SFRD) and black hole accretion rate density (BHARD). The model naturally explains why the ratio of the comoving densities of galaxies and AGN is constant with redshift and gives a remarkably simple framework for considering the role of supermassive black holes in galaxy evolution.