A general study of regular and singular black hole solutions in Einstein's conformal gravity

TL;DR

This paper investigates properties of two black hole solutions in Einstein's conformal gravity, analyzing their geodesics, accretion disk efficiency, and horizon stability, revealing differences between regular and singular solutions.

Contribution

It introduces and compares regular and singular black hole solutions derived from Kerr metrics via conformal rescaling, and assesses their physical and stability properties.

Findings

Regular black hole horizon cannot be destroyed.

Singular black hole horizon can be destroyed.

Constraints on parameter L from accretion disk efficiency.

Abstract

We study some general properties of two black hole solutions in Einstein's conformal gravity. Both solutions can be obtained from the Kerr metric with a suitable conformal rescaling, which leads, respectively, to a regular and a singular spacetime. In addition to the mass $M$ and the spin angular momentum $J$ of the black hole, these solutions are characterized by a new parameter, $L$, which may be expected to be of the order of the black hole mass. We study the geodesic motion and we calculate the radiative efficiency of a putative accretion disk around these black holes, which allows us to get an estimate of an upper bound on the value of $L$. Lastly, we explore the possibility of "destroying" the event horizon of these black holes. Within our approach, we are not able to destroy the event horizon of the regular black hole solution, while we can in the case of the singular one.