Shadow of novel rotating black holes in GR coupled to nonlinear electrodynamics and constraints from EHT results

TL;DR

This paper investigates the optical properties and shadow of a novel rotating black hole in GR coupled with nonlinear electrodynamics, analyzing how spin, charge, and NED parameters affect shadow shape and constraining these parameters using EHT observations.

Contribution

It introduces a new regular rotating black hole solution in GR with NED, analyzes its shadow and photon orbits, and constrains model parameters using EHT data.

Findings

Increased spin and charge increase shadow distortion.

Shadow area and oblateness decrease with NED parameters.

Constraints on black hole charge and NED parameters from EHT data.

Abstract

We study the optical properties of spacetime around a novel regular black hole (BH) in general relativity (GR) coupled to nonlinear electrodynamics (NED), which is asymptotically flat. First, we study the angular velocity and Lyapunov exponent in unstable photon circular orbits in the novel spherically symmetric BH spacetime. Later, the rotating regular BH solution is obtained using the Newmann-Janis algorithm, and the event horizon properties of the BH are determined. We analyze the effective potential for the circular motion of photons in the spacetime of the novel rotating BH. Also, we analyze the photon sphere around the novel BH and its shadow using celestial coordinates. We obtain that an increase of the BH spin and charge as well as NED field nonlinearity parameters causes an increase in the distortion parameter of the BH shadow, while, the area of the shadow and its oblateness decrease. Moreover, we also obtain the constraint values for the BH charge and the nonlinearity parameters using Event Horizon Telescope data from shadow sizes of supermassive BHs Sgr A* and M87*. Finally, the emission rate of BH evaporation through Hawking radiation is also studied.