The Innermost Extremes of Black Hole Accretion

TL;DR

This paper discusses recent advances in X-ray spectral-timing techniques that map the innermost regions of black hole accretion disks, revealing details about the event horizon, corona, and relativistic effects in extreme AGN and stellar-mass black holes.

Contribution

It presents new insights into the structure and behavior of the innermost accretion regions near black holes using spectral blurring and reverberation analysis.

Findings

Mapping of regions within 20 gravitational radii of black holes.

Detection of regions within 1 gravitational radius in high-spin, low-state AGN.

Revelation of corona location, size, and operation near black holes.

Abstract

The inner 20 gravitational radii around the black hole at the centre of luminous Active Galactic Nuclei and stellar mass Black Hole Binaries are now being routinely mapped by X-ray spectral-timing techniques. Spectral blurring and reverberation of the reflection spectrum are key tools in this work. In the most extreme AGN cases with high black hole spin, when the source appears in a low state, observations probe the region within 1 gravitational radius of the event horizon. The location, size and operation of the corona, which generates the power-law X-ray continuum, are also being revealed.