Searching for deviations from general relativity around stellar-mass black holes

We performed a search in the literature for observational measurements of the inner radius of the accretion disk around stellar-mass black holes.

We selected the smallest values measured when the disk was in high/soft state, made them homogeneous by taking into account the most recent and more reliable values of mass, spin, viewing angle, and distance from the Earth, and compared with the expectations of the Kerr metric.

We do not find any significant deviation. Some doubtful cases can be easily understood as due to specific states of the object during the observation or instrumental biases. We used these measurements to set a lower limit of the ξ parameter of the asymptotic safe gravity.