Particle dynamics and optical appearance of charged spherically symmetric black holes in bumblebee gravity

TL;DR

This paper investigates the effects of Lorentz-violation and charge parameters on the particle dynamics, shadow, and optical appearance of charged black holes in bumblebee gravity, providing observational constraints and distinguishing features.

Contribution

It offers a detailed analysis of black hole shadows and optical properties in bumblebee gravity, including observational constraints and comparison with other black hole models.

Findings

Effective potential peaks are affected oppositely by Lorentz-violation and charge.

Shadow and photon sphere radii decrease with increasing parameters, smaller than in standard black holes.

Parameter constraints are derived from Event Horizon Telescope data.

Abstract

In this paper, we study the particle dynamics, shadow, and optical appearance of charged black holes (BHs) in bumblebee gravity. Firstly, we find that the Lorentz-violation parameter l and charge parameter Q have opposite effects on the peak of the effective potential by analyzing timelike geodesics, and the radius of the innermost stable circular orbit (ISCO) decreases as the BH parameters l and Q increase. We also explore the behaviors of particle energy, angular momentum, and Keplerian frequency. Secondly, for null geodesics, both the photon sphere radius and the shadow radius decrease with increasing l and Q, and are consistently smaller than those of the Reissner-Nordstrom black hole (RNBH) and Schwarzschild-like BH. And based on observational data reported by the Event Horizon Telescope (EHT) Collaboration, we constrain the parameters l and Q by using the shadow radius data of Sgr A*. Thirdly, we explore the observation characteristics of charged BHs under three thin disk accretion models. The results show that, compared to RNBH, the increase of l leads to a greater thickness of the photon rings and lensed rings. However, due to their extremely narrow ranges, the contributions are small, and the observed intensities are mainly contributed by the direct emissions. Moreover, when the parameter l is fixed, the peaks of the observed intensities of rings decrease with increasing Q for the same emission model, and it is always lower than the corresponding value for Schwarzschild-like BH. These findings contribute to distinguishing bumblebee charged black holes (BCBHs) from other types of BHs based on their optical appearance.