Charged black-bounce spacetimes: Photon rings, shadows and observational appearances

TL;DR

This paper analyzes the photon rings, shadows, and observational appearances of charged black-bounce spacetimes, revealing how charge influences observable features and comparing findings with recent astronomical observations.

Contribution

It provides a detailed geodesic analysis of charged black-bounce spacetimes and classifies light trajectories to understand their observational signatures.

Findings

Large charge increases observed intensity

Charge decreases the apparent size of shadows

Photon rings are intrinsic to spacetime geometry

Abstract

The photon ring, shadow and observational appearance of the emission originating near a charged black-bounce are investigated. Based on the geodesic analysis, we determine the upper and lower limits of critical impact parameters of a charged black-bounce. In particular, we find that the charged black-bounce shares the same critical impact parameter with the Reissner-Nordst\"om black hole. In addition, we classify the light trajectories coming from the region near the charged black-bounce by utilizing the rays tracing procedure, and then investigate the observational appearance of the emissions from a thin disk accretion and a spherically symmetric infalling accretion. We reveal that a large charge increases the observed intensity but decreases the apparent size of shadows, and that the photon ring presents the intrinsic property of a spacetime geometry, which is independent of the types of the two accretions. Our results are in good agreement with the recent observations.