Rotating regular black holes in conformal massive gravity

TL;DR

This paper constructs and analyzes rotating regular black holes in conformal massive gravity, examining their shadows, deflection angles, and observational constraints, revealing how parameters influence observable features compared to Kerr black holes.

Contribution

It introduces a new class of rotating regular black hole solutions in conformal massive gravity and studies their observable properties and constraints.

Findings

Shadow size varies with parameters, larger for positive scalar charge and negative hair parameter.

Deflection angles are significantly affected by the conformal scale factor L.

Observational constraints on the scalar charge Q are derived from EHT data on M87*.

Abstract

In this paper, we use a suitable conformal rescaling to construct static and rotating regular black holes in conformal massive gravity. The new metric is characterized by the mass $M$, the "scalar charge" $Q$, the angular momentum parameter $a$, the "hair parameter" $\lambda$, and the conformal scale factor encoded in the parameter $L$. We explore the shadow images and the deflection angles of relativistic massive particles in the spacetime geometry of a rotating regular black hole. For $\lambda \neq 0$ and $Q > 0$, the shadow is larger than the shadow of a Kerr black hole. In particular, if $\lambda < 0$, the shadow radius increases considerably. For $\lambda \neq 0$ and $Q < 0$, the shadow is smaller than the shadow of a Kerr black hole. Additionally we put observational constraints on the parameter $ Q $ using the latest Event Horizon Telescope (EHT) observation of the supermassive black hole M87*. Lastly, using the Gauss-Bonnet theorem, we show that the deflection angle of massive particles is strongly affected by the parameter $L$. The deflection angle might be used to distinguish rotating regular black holes from rotating singular black holes.