Rapid formation of black holes in galaxies: a self-limiting growth mechanism

TL;DR

This study uses fluid dynamical simulations to show how gas inflow in barred galaxies can rapidly form black holes, but self-limits growth once a nuclear mass exceeds about 1% of the disk, impacting galaxy evolution models.

Contribution

It demonstrates a self-limiting mechanism for black hole growth driven by bar-induced gas inflow and nuclear ring formation in disk galaxies.

Findings

Gas inflow stalls at a nuclear ring when central mass exceeds ~1% of disk mass.

Nuclear ring radius increases linearly with central mass.

Bar-driven inflow can rapidly seed black hole formation in early galaxy stages.

Abstract

We present high-quality fluid dynamical simulations of isothermal gas flows in a rotating barred potential. We show that a large quantity of gas is driven right into the nucleus of a model galaxy when the potential lacks a central mass concentration, but the inflow stalls at a nuclear ring in comparison simulations that include a central massive object. The radius of the nuclear gas ring increases linearly with the mass of the central object. We argue that bars drive gas right into the nucleus in the early stages of disk galaxy formation, where a nuclear star cluster and perhaps a massive black hole could be created. The process is self-limiting, however, because inflow stalls at a nuclear ring once the mass of gas and stars in the nucleus exceeds ~1% of the disk mass, which shuts off rapid growth of the black hole. We briefly discuss the relevance of these results to the seeding of massive black holes in galaxies, the merger model for quasar evolution, and the existence of massive black holes in disk galaxies that lack a significant classical bulge.