X-ray reflection in accreting stellar-mass black hole systems

TL;DR

This paper models X-ray reflection features, especially iron lines, in accreting stellar-mass black hole systems, highlighting differences between hot and cool accretion discs in their spectral signatures.

Contribution

It provides a self-consistent calculation of reflection spectra from hot accretion discs with hydrostatic atmospheres, comparing them to cooler disc models.

Findings

Reflection spectra vary significantly with disc temperature and illumination strength.

Hot accretion discs produce distinct reflection features compared to cooler discs.

Results aid in interpreting X-ray spectra of black hole systems.

Abstract

The X-ray spectra of accreting stellar-mass black hole systems exhibit spectral features due to reflection, especially broad iron K alpha emission lines. We investigate the reflection by the accretion disc that can be expected in the high/soft state of such a system. First, we perform a self-consistent calculation of the reflection that results from illumination of a hot, inner portion of the disc with its atmosphere in hydrostatic equilibrium. Then we present reflection spectra for a range of illumination strengths and disc temperatures under the assumption of a constant-density atmosphere. Reflection by a hot accretion disc differs in important ways from that of a much cooler disc, such as that expected in an active galactic nucleus.