Black hole accretion discs

TL;DR

This paper provides a comprehensive overview of black hole accretion disc models, covering non-relativistic equations, steady-state solutions, thermal-viscous instabilities, advection effects, and general relativistic formalism.

Contribution

It offers an integrated review of theoretical models and observational comparisons for accretion discs around black holes, including recent developments in relativistic and advection-dominated models.

Findings

Comparison of steady-state solutions with observations

Explanation of X-ray transient phenomena via disc instability models

Illustration of advection's role in accretion flows

Abstract

This is an introduction to models of accretion discs around black holes. After a presentation of the non-relativistic equations describing the structure and evolution of geometrically thin accretion discs we discuss their steady-state solutions and compare them to observation. Next we describe in detail the thermal-viscous disc instability model and its application to dwarf novae for which it was designed and its X-ray irradiated-disc version which explains the soft X--ray transients, i.e. outbursting black-hole low-mass X-ray binaries. We then turn to the role of advection in accretion flows onto black holes illustrating its action and importance with a toy model describing both ADAFs and slim discs. We conclude with a presentation of the general-relativistic formalism describing accretion discs in the Kerr space-time.