Testing the Kerr-nature of stellar-mass black hole candidates by combining the continuum-fitting method and the power estimate of transient ballistic jets

TL;DR

This paper proposes a method to test whether stellar-mass black hole candidates are true Kerr black holes by combining X-ray continuum-fitting with radio jet power measurements, aiming to detect deviations from General Relativity.

Contribution

It introduces a novel approach that integrates existing X-ray data with radio jet observations to directly test the Kerr nature of black hole candidates.

Findings

Potential to distinguish Kerr from non-Kerr black holes

Extension of continuum-fitting method with jet power data

Framework for observational tests of black hole spacetime geometry

Abstract

Astrophysical black hole candidates are thought to be the Kerr black holes predicted by General Relativity, as these objects cannot be explained otherwise without introducing new physics. However, there is no observational evidence that the space-time around them is really described by the Kerr solution. The Kerr black hole hypothesis can be tested with the already available X-ray data by extending the continuum-fitting method, a technique currently used by astronomers to estimate the spins of stellar-mass black hole candidates. In general, we cannot put a constraint on possible deviations from the Kerr geometry, but only on some combination between these deviations and the spin. The measurement of the radio power of transient jets in black hole binaries can potentially break this degeneracy, thus allowing for testing the Kerr-nature of these objects.