Images of nonsingular nonrotating black holes in conformal gravity

TL;DR

This paper studies the images of nonsingular black holes in conformal gravity, showing that while the shadow radius remains unaffected, the conformal factor influences the black hole's intensity image.

Contribution

It introduces a detailed analysis of accretion disk images around conformally related nonsingular black holes, highlighting the impact of conformal factors on observable features.

Findings

Shadow radius remains unchanged by conformal factors.

Conformal factor affects the intensity distribution of black hole images.

Comparison with Schwarzschild black hole highlights unique conformal gravity signatures.

Abstract

The accretion disk around a black hole and its emissions play an essential role in theoretical analysis of the black hole image. In the literature, two analytical toy models of accretions are widely adopted: the spherical model and the thin disk model. They are different geometrically but both thin optically. We polish them for free-falling accretions around static spherical black holes. As an application, we investigate the images of a class of nonsingular black holes conformally related to the Schwarzschild black hole. These black holes are vacuum solutions of a family of conformal gravity theories. Results are compared with the Schwarzschild black hole of the same mass. Our results indicate that the conformal factor does not affect the shadow radius seen by distant observers, but it leaves an imprint on the intensity image of black hole.