Accretion Geometry of Black Hole X-ray Binaries: Insights from X-ray Observations

TL;DR

This paper reviews how X-ray observations reveal the structure of accretion disks around black hole X-ray binaries, highlighting recent findings on disk geometry and jet connections across different accretion states.

Contribution

It summarizes current X-ray spectroscopic techniques and insights into accretion geometry and disk-corona-jet interactions in black hole X-ray binaries.

Findings

Accretion disks can extend close to the innermost stable circular orbit in bright hard states.

X-ray spectroscopic studies provide key insights into accretion geometry.

Hints of disk-corona-jet connections are discussed.

Abstract

The accretion-ejection activities of black holes play a vital role in shaping the Universe. Bright and recurrent black hole X-ray binaries are ideal objects for studying accretion physics across a wide range of accretion rates, providing insights into the understanding of their supermassive counterparts. This short review summarizes X-ray techniques capable of measuring accretion geometry, our current understanding, and open questions. In particular, X-ray spectroscopic studies indicate that the accretion disk can extend close to the innermost stable circular orbit in the bright hard state. Some hints of disk-corona-jet connections are also discussed.