Testing conformal gravity with astrophysical black holes

TL;DR

This paper tests a conformal gravity black hole model against astrophysical data, finding that the model's parameter must be below a certain threshold to match observed X-ray emissions.

Contribution

It introduces a singularity-free rotating black hole solution in conformal gravity and constrains its parameters using astrophysical observations.

Findings

Parameter L/M must be less than 1.2 based on X-ray data

Photon trajectories remain unchanged in the conformal black hole

Accretion disk structure is affected by the parameter L

Abstract

Weyl conformal symmetry can solve the problem the spacetime singularities present in Einstein's gravity. In a recent paper, two of us have found a singularity-free rotating black hole solution in conformal gravity. In addition to the mass $M$ and the spin angular momentum $J$ of the black hole, the new solution has a new parameter, $L$, which here we consider to be proportional to the black hole mass. Since the solution is conformally equivalent to the Kerr metric, photon trajectories are unchanged, while the structure of an accretion disk around a black hole is affected by the value of the parameter $L$. In this paper, we show that X-ray data of astrophysical black holes require $L/M < 1.2$.