Massive black holes in stellar systems: 'quiescent' accretion and luminosity

TL;DR

This paper models the expected luminosities of black holes in various stellar systems by analyzing available gas from stellar mass loss and assessing their detectability in the local universe.

Contribution

It introduces a model to estimate luminosities of quiescent black holes across different stellar systems based on stellar mass loss and accretion assumptions.

Findings

Black holes in stellar systems can have low but detectable luminosities.

The model predicts luminosity ranges for black holes in different environments.

Detectability of quiescent black holes depends on system properties and observational sensitivity.

Abstract

Only a small fraction of local galaxies harbor an accreting black hole, classified as an active galactic nucleus (AGN). However, many stellar systems are plausibly expected to host black holes, from globular clusters to nuclear star clusters, to massive galaxies. The mere presence of stars in the vicinity of a black hole provides a source of fuel via mass loss of evolved stars. In this paper we assess the expected luminosities of black holes embedded in stellar systems of different sizes and properties, spanning a large range of masses. We model the distribution of stars and derive the amount of gas available to a central black hole through a geometrical model. We estimate the luminosity of the black holes under simple, but physically grounded, assumptions on the accretion flow. Finally we discuss the detectability of 'quiescent' black holes in the local Universe.