Black hole evolution: I. Supernova-regulated black hole growth

TL;DR

This study uses high-resolution cosmological simulations to investigate how supernova feedback influences the growth of supermassive black holes in galaxies at high redshift, highlighting the role of supernova efficiency in regulating black hole accretion.

Contribution

It demonstrates the impact of supernova feedback efficiency on black hole growth and galaxy evolution in a cosmological context, using detailed simulations of a galaxy progenitor at z=2.

Findings

Supernova feedback efficiency determines early black hole growth rates.

Efficient supernova feedback prevents cold gas accumulation and star formation in early galaxies.

Black hole growth becomes sustained as the galaxy's mass increases and can confine nuclear inflows.

Abstract

The growth of a supermassive black hole (BH) is determined by how much gas the host galaxy is able to feed it, which in turn is controlled by the cosmic environment, through galaxy mergers and accretion of cosmic flows that time how galaxies obtain their gas, but also by internal processes in the galaxy, such as star formation and feedback from stars and the BH itself. In this paper, we study the growth of a 10^12 Msun halo at z=2, which is the progenitor of al group of galaxies at z=0, and of its central BH by means of a high-resolution zoomed cosmological simulation, the Seth simulation. We study the evolution of the BH driven by the accretion of cold gas in the galaxy, and explore the efficiency of the feedback from supernovae (SNe). For a relatively inefficient energy input from SNe, the BH grows at the Eddington rate from early times, and reaches self-regulation once it is massive enough. We find that at early cosmic times z>3.5, efficient feedback from SNe forbids the formation of a settled disc as well as the accumulation of dense cold gas in the vicinity of the BH and starves the central compact object. As the galaxy and its halo accumulate mass, they become able to confine the nuclear inflows provided by major mergers and the BH grows at a sustained near-to-Eddington accretion rate. We argue that this mechanism should be ubiquitous amongst low-mass galaxies, corresponding to galaxies with a stellar mass below <10^9 Msun in our simulations.