X-ray Spectroscopy of Disk Winds in Black Hole X-ray Binaries

TL;DR

This paper reviews the study of disk winds in black hole X-ray binaries, emphasizing recent advances with XRISM's high-resolution spectroscopy that improve understanding of wind mechanisms and their effects on accretion.

Contribution

It provides a comprehensive overview of past findings and discusses how XRISM's capabilities are advancing the understanding of disk wind launching mechanisms and their influence.

Findings

Pre-XRISM observations identified blueshifted, ionized absorption lines.

XRISM's high spectral resolution enhances wind detection and analysis.

Future observations will clarify wind launching processes.

Abstract

Powerful outflows along the accretion disk, known as disk winds, are sometimes launched in black hole X-ray binaries. These winds often manifest themselves in X-ray spectra as blueshifted, highly ionized absorption lines. Previous observations suggest that the mass loss rate from the disk due to disk winds can be comparable to or even more than the mass accretion rate onto the black hole, indicating that disk winds likely play crucial roles in shaping the accretion disk structure and affecting the surrounding environment. However, the mechanisms driving these winds, as well as how their structure changes in response to variations in the mass accretion rate, remain poorly understood. The X-ray Imaging and Spectroscopy Mission (XRISM), launched in September 2023, is equipped with Resolve, a cutting-edge X-ray micro-calorimeter that delivers unprecedented spectral resolution. Resolve is expected to significantly advance our understanding of wind launching mechanisms and their impact on accretion processes and environments. In this article, we review the progress made in the pre-XRISM era, highlight key results obtained from XRISM observations to date, and outline future prospects.