Strong gravitational lensing and shadow constraint from M87* of slowly rotating Kerr-like black hole

TL;DR

This paper investigates how Lorentz violation in Einstein bumblebee gravity affects gravitational lensing and black hole shadow observations of M87*, suggesting future EHT data could test these deviations from general relativity.

Contribution

It applies Einstein bumblebee gravity to model slowly rotating Kerr-like black holes and analyzes the impact of Lorentz violation on lensing and shadow features, providing potential observational constraints.

Findings

LV parameter significantly affects lensing observables

Black hole shadow luminosity depends on LV parameter

Future EHT observations could constrain Lorentz violation

Abstract

Motivated by (i) more and more interest in strong gravitational lensing by supermassive black holes due to the achievement of EHT observations, (ii) the ongoing popular topic on the possibility of Lorentz symmetry being broken in gravitation and its consequences, we will apply the Einstein bumblebee gravity with Lorentz violation (LV) to the study of strong gravitational lensing effect and the black hole shadow of slowly rotating Kerr-like black hole. In the strong gravitational lensing sector, we first calculate the deflection angel; then treating the slowly rotating Kerr-like black hole as supermassive M87* black hole, we evaluate the gravitational lensing observables (position, separation and magnification) and the time delays between the relativistic images. In the black hole shadow sector, we show the effect of LV parameter on the luminosity of the black hole shadow and photon sphere using the infalling spherical accretion. Moreover, we explore the dependence of various shadow observables on the LV parameter, and then give the possible constraint on the LV parameter by M87* black hole of EHT observations. We find that the LV parameter show significant effect on the strong gravitational lensing effect, the black hole shadow and photon sphere luminosity by accretion material. Our results point out that the future generations of EHT observation may help to distinguish the Einstein bumblebee gravity from GR, and also give a possible constrain on the LV parameter.