By Cosimo Bambi

The study of relativistically blurred reflection features in the X-ray spectra of accreting black holes can be a powerful tool to probe the strong gravity region around those compact objects, study the morphology of the accreting matter, measure black hole spins, and even test Einstein’s theory of general relativity in the strong-field regime. In the last decade, there have been significant advancements in the analysis of these features, thanks to more sophisticated astrophysical models and new observational facilities.

The paper reviews the state-of-the-art in the field and the roadmap for future developments. Athena, with its microcalorimeter energy resolution and large collecting area, promises to provide unprecedented high-quality data that will further boost the development of the field. With Athena, precise black hole spin measurements will be possible for hundreds of sources, compared with the tens we have to date, and we will eventually enter an era of precision tests of general relativity with black hole X-ray data.

Access to the manuscript in ADS.