Testing conformal gravity with the supermassive black hole in 1H0707-495

TL;DR

This paper tests conformal gravity by analyzing X-ray data from the supermassive black hole in 1H0707-495, constraining the deviation parameter L/M to be less than 0.45, thus supporting the Kerr black hole solution.

Contribution

It provides a more precise constraint on the conformal gravity parameter L/M using advanced X-ray reflection modeling of astrophysical black hole data.

Findings

L/M < 0.45 at 90% confidence level

Supports Kerr black hole solution in conformal gravity

Improves previous constraints on the parameter L/M

Abstract

Recently, two of us have found a family of singularity-free rotating black hole solutions in Einstein's conformal gravity. These spacetimes are characterized by three parameters: the black hole mass $M$, the black hole spin angular momentum $J$, and a parameter $L$ that is not specified by the theory but can be expected to be proportional to the black hole mass $M$. The Kerr black hole solution of Einstein's gravity is recovered for $L = 0$. In a previous paper, we showed that X-ray data of astrophysical black holes require $L/M < 1.2$. In the present paper, we report the results of a more sophisticated analysis. We apply the X-ray reflection model {\sc relxill\_nk} to \textsl{NuSTAR} and \textsl{Swift} data of the supermassive black hole in 1H0707-495. We find the constraint $L/M < 0.45$ (90% confidence level).