Towards precision measurements of accreting black holes using X-ray reflection spectroscopy

TL;DR

This paper reviews how X-ray reflection spectroscopy can precisely measure black hole properties and test general relativity, emphasizing recent advances and remaining challenges in modeling and observations.

Contribution

It provides a comprehensive overview of current relativistic reflection models, their assumptions, and recent progress in using X-ray spectra to measure black hole spins and test fundamental physics.

Findings

Advances in astrophysical models improve measurement accuracy.

X-ray reflection spectroscopy can probe strong gravity regions.

Recent efforts aim to test Einstein's theory in extreme conditions.

Abstract

Relativistic reflection features are commonly observed in the X-ray spectra of accreting black holes. In the presence of high quality data and with the correct astrophysical model, X-ray reflection spectroscopy can be quite a powerful tool to probe the strong gravity region, study the morphology of the accreting matter, measure black hole spins, and possibly test Einstein's theory of general relativity in the strong field regime. In the last decade, there has been significant progress in the development of the analysis of these features, thanks to more sophisticated astrophysical models and new observational facilities. Here we review the state-of-the-art in relativistic reflection modeling, listing assumptions and simplifications that may affect, at some level, the final measurements and may be investigated better in the future. We review black hole spin measurements and the most recent efforts to use X-ray reflection spectroscopy for testing fundamental physics.