Shadow of rotating regular black holes

TL;DR

This paper investigates the shadows of rotating regular black holes, analyzing how various parameters and plasma environment influence the shadow size and distortion, providing insights into observational signatures of such black holes.

Contribution

It presents a comparative analysis of shadows for different rotating regular black holes and explores the impact of plasma environment on their apparent size.

Findings

Shadow radius decreases with increasing parameters.

Shadow distortion increases with parameter values.

Plasma environment enlarges the shadow due to gravitational redshift and plasma density.

Abstract

We study the shadows cast by the different types of rotating regular black holes viz. Ay\'on-Beato-Garc\'ia {(ABG)}, Hayward, and Bardeen. These black holes have in addition to the total mass ($M$) and rotation parameter ($a$), different parameters as electric charge ($Q$), deviation parameter ($g$), and magnetic charge ($g_{*}$), respectively. Interestingly, the size of the shadow is affected by these parameters in addition to the rotation parameter. We found that the radius of the shadow in each case decreases monotonically and the distortion parameter increases when the value of these parameters increase. A comparison with the standard Kerr case is also investigated. We have also studied the influence of the plasma environment around regular black holes to discuss its shadow. The presence of the plasma affects the apparent size of the regular black hole's shadow to be increased due to two effects (i) gravitational redshift of the photons and (ii) radial dependence of plasma density.