Gravitational lensing and shadow by a Schwarzschild-like black hole in metric-affine bumblebee gravity

TL;DR

This paper explores how a Schwarzschild-like black hole in metric-affine bumblebee gravity affects gravitational lensing and shadow formation, providing a formalism for higher-order light bending corrections and estimating Lorentz symmetry breaking effects from observational data.

Contribution

It introduces a generalized formalism for higher-order light bending corrections in non-flat spacetimes and applies it to bumblebee gravity, linking theoretical predictions with observational constraints.

Findings

Derived light deflection angles and Einstein ring sizes in bumblebee gravity.

Estimated upper bounds on Lorentz symmetry breaking coefficient from observational data.

Analyzed black hole shadow characteristics within the modified gravity framework.

Abstract

In this paper, we investigate the gravitational lensing effect and the shadow around a Schwarzschild-like black hole in metric-affine bumblebee gravity, which leads to the Lorentz symmetry breaking. We first present a generalized formalism for calculating higher-order corrections to light weak bending angle in a static, spherically symmetric and not asymptotically flat spacetime, and then applying this general formalism to the metric-affine bumblebee gravity. Moreover, we derive the light deflection angle and the size of the Einstein ring within the weak field in this scenario. In addition, we analyze the black hole shadow in this theory framework. By using observational data from the Einstein's ring of the galaxy ESO325-G004 and the black hole shadow of the ${\rm M}87$ galaxy, we estimate the upper bounds of the Lorentz symmetry breaking coefficient $\ell$, respectively.