We extend our previous work on tests of the Kerr black hole hypothesis using X-ray reflection spectroscopy and we infer observational constraints on the Johannsen deformation parameter ϵ3. We analyze a NuSTAR observation of the stellar-mass black hole in GS 1354-645, Suzaku data of the supermassive black holes in Ark 564, 1H0419-577, and PKS 0558-504, and some simultaneous XMM-Newton and NuSTAR observations of the supermassive black hole in MCG-6-30-15. All our measurements of ϵ3 are consistent with the Kerr metric and we find quite strong constraints from Ark 564 and MCG-6-30-15. We discuss the implications of our results and the next steps to improve our tests.
Cite
@article{arxiv.1903.04071,
title = {Constraining the Johannsen deformation parameter $\epsilon_3$ with black hole X-ray data},
author = {Ashutosh Tripathi and Askar B. Abdikamalov and Dimitry Ayzenberg and Cosimo Bambi and Sourabh Nampalliwar},
journal= {arXiv preprint arXiv:1903.04071},
year = {2019}
}