Self-regulated growth of supermassive black holes in galaxies as the origin of the optical and X-ray luminosity functions of quasars

Abstract

We postulate that supermassive black holes grow in the centers of galaxies until they unbind the galactic gas that feeds them. We show that the corresponding self-regulation condition yields a correlation between black hole mass (Mbh) and galaxy velocity dispersion (σ) as inferred in the local universe and recovers the observed optical and X-ray luminosity functions of quasars at redshifts up to z ∼ 6 based on the hierarchical evolution of galaxy halos in a Λ-dominated cold dark matter cosmology. With only one free parameter and a simple algorithm, our model yields the observed evolution in the number density of optically bright or X-ray-faint quasars with 2≲z≲6 across 3 orders of magnitude ..