The Demography of Super-Massive Black Holes: Growing Monsters at the Heart of Galaxies

TL;DR

This paper reviews the growth and evolution of supermassive black holes in galaxies, highlighting how their properties are linked to galaxy features and discussing new numerical results on black hole mass functions.

Contribution

It introduces a novel numerical code to model black hole growth and clustering, providing new insights into their evolution independent of specific models.

Findings

Constraints on black hole growth history from local and cosmic data

Development of a numerical code for evolving black hole mass functions

Connections between black hole evolution and galaxy development

Abstract

Supermassive black holes (BHs) appear to be ubiquitous at the center of all galaxies which have been observed at high enough sensitivities and resolution with the Hubble Space Telescope. Their masses are found to be tightly linked with the masses and velocity dispersions of their host galaxies. On the other hand, BHs are widely held to constitute the central engines of quasars and active galactic nuclei (AGN) in general. It is however still unclear how BHs have grown, and whether they have co-evolved with their hosts. In this Review I discuss how, in ways independent of specific models, constraints on the growth history of BHs and their host galaxies have been set by matching the statistics of local BHs to the emissivity, number density, and clustering properties of AGNs at different cosmological epochs. I also present some new results obtained through a novel numerical code which evolves the BH mass function and clustering adopting broad distributions of Eddington ratios. I finally review BH evolution in a wider cosmological context, connecting BH growth to galaxy evolution.