Testing the space-time geometry around black hole candidates with the available radio and X-ray data

TL;DR

This paper reviews methods for testing whether black hole candidates conform to Kerr black hole predictions by analyzing electromagnetic signals from accretion disks using radio and X-ray data.

Contribution

It discusses how electromagnetic observations can be used to test the Kerr hypothesis and constrain deviations from General Relativity around black hole candidates.

Findings

Electromagnetic radiation analysis can reveal space-time geometry.

Current data can test Kerr black hole predictions.

Constraints on deviations from General Relativity are possible.

Abstract

Astrophysical black hole candidates are thought to be the Kerr black holes predicted by General Relativity, but the actual nature of these objects has still to be proven. The Kerr black hole hypothesis can be tested by observing strong gravity features and check if they are in agreement with the predictions of General Relativity. In particular, the study of the properties of the electromagnetic radiation emitted by the gas of the accretion disk can provide information on the geometry of the space-time around these objects and constrain possible deviations from the Kerr background.