Multi-scale simulations of black hole accretion in barred galaxies: Self-gravitating disk models

TL;DR

This study uses multi-scale simulations to explore how stellar bars influence gas dynamics and black hole growth in spiral galaxies, revealing the importance of large-scale structures on accretion rates and final black hole masses.

Contribution

It introduces a multi-scale simulation approach to analyze the impact of stellar bars on gas accretion and black hole growth in barred spiral galaxies, considering various initial conditions.

Findings

Accretion rates depend strongly on kiloparsec-scale gas flow.

Black hole masses can reach up to 10^9 solar masses within 1.6 Gyr.

Growth rates decline at the Eddington limit.

Abstract

Due to the non-axisymmetric potential of the central bar, barred spiral galaxies form, in addition to their characteristic arms and bar, a variety of structures within the thin gas disk, like nuclear rings, inner spirals and dust-lanes. These structures in the inner kiloparsec are most important to explain and understand the rate of black hole feeding. The aim of this work is to investigate the influence of stellar bars in spiral galaxies on the thin self-gravitating gas disk. We focus on the accretion of gas onto the central supermassive black hole and its time-dependent evolution. We conduct multi-scale simulations simultaneously resolving the galactic disk and the accretion disk around the central black-hole. We vary in all simulations the initial gas disk mass. As additional parameter we choose either the gas temperature for isothermal simulations or the cooling timescale in case of non-isothermal simulations. Accretion is either driven by a gravitationally unstable or clumpy accretion disk or by energy dissipation in strong shocks. Most simulations show a strong dependence of the accretion rate at the outer boundary of the central accretion disk ($r< 300~\mathrm{pc}$) on the gas flow at kiloparsec scales. The final black hole masses reach up to $\sim 10^9 M_\odot$ after $1.6~\mathrm{Gyr}$. Our models show the expected influence of the Eddington limit and a decline in growth rate at the corresponding sub-Eddington limit.