Strong Gravitational Lensing by a Black Hole with a Global Monopole in Kalb-Ramond Bumblebee Gravity

TL;DR

This paper explores how a black hole's gravitational lensing and shadow are affected by bumblebee gravity, characterized by a global monopole charge and Lorentz symmetry breaking, providing potential observational tests.

Contribution

It introduces a detailed analysis of strong lensing and shadow features of black holes within bumblebee gravity, incorporating monopole charge and Lorentz violation effects.

Findings

Global monopole charge alters photon sphere and lensing observables.

Lorentz-violating parameters significantly modify shadow structure.

Results suggest observable signatures for testing bumblebee gravity.

Abstract

We investigate the strong gravitational lensing and shadow properties of the black hole in the context of bumblebee gravity, characterized by a global monopole charge $\kappa\eta^2$ and a Lorentz symmetry breaking parameter $\gamma$. We compute the deflection angles of light passing near the black hole in strong deflection limit, and estimate key lensing observables, including relativistic Einstein rings, absolute magnifications, image separations, and flux ratios, for astrophysical black holes. The black hole shadow is analyzed using the apparent angular size $\theta_{\rm Shadow} = 2\,\theta_{\infty}$ in the limiting photon orbit. Furthermore, we study the modification of the shadow structure in the presence of a radially infalling, optically thin accretion flow within a generalized framework. Our results indicate that both the global monopole charge and Lorentz-violating parameters significantly influence the photon sphere, lensing observables, and shadow morphology, potentially providing observational signatures for testing bumblebee gravity in the strong-field regime.