A short observational view of black hole X-ray binaries with INTEGRAL

TL;DR

This paper reviews how INTEGRAL observations enhance understanding of black hole X-ray binaries, focusing on high-energy emissions, variability, and polarization to probe extreme gravity and accretion processes.

Contribution

It highlights INTEGRAL's unique role in studying high-energy phenomena and variability in black hole X-ray binaries, advancing knowledge of their emission mechanisms.

Findings

INTEGRAL provides coverage above spectral cutoff energies.

Long-term monitoring reveals variability patterns.

Polarization measurements inform on emission processes.

Abstract

Accreting black holes are unique tools to understand the physics under extreme gravity. While black hole X-ray binaries differ vastly in mass from AGN, their accretion and ejection flows are assumed to be essentially similar. Black hole X-ray binaries or microquasars are, however, quasars for the impatient as variability timescales scale directly with mass. State changes, i.e., strong variations in emission properties, in black hole X-ray binaries can happen within hours and whole outburst cycles within months to years. But our understanding of the drivers of such changes and the contributions of individual accretion and ejection components to the overall emission is still lacking. Here, I highlight some of the INTEGRAL's unique contributions to the understanding of black hole X-ray binaries through its coverage of the energies above the spectral cutoff, its long uninterrupted monitoring observations and the measurements of hard X-ray / soft $\gamma$-ray polarization.