Thermodynamics and Optical Properties of Charged Black Holes in Bumblebee gravity Sourced by a Cloud of Strings

TL;DR

This paper explores how Lorentz-violating modifications in bumblebee gravity affect the thermodynamics, optical properties, and classical tests of charged black holes surrounded by a string cloud, revealing potential observational signatures.

Contribution

It presents exact solutions for charged black holes in bumblebee gravity with a string cloud and analyzes their thermodynamic and optical properties, highlighting effects of Lorentz violation.

Findings

Lorentz violation alters black hole temperature and entropy.

Photon sphere and shadow are affected by Lorentz-violating parameters.

Solar System tests constrain Lorentz-violating effects.

Abstract

In theories where the Lorentz symmetry of gravity is spontaneously broken, a non-minimally coupled bumblebee vector field acquires a nonzero vacuum expectation value, leading to modifications of standard General Relativity (GR). In this work, we investigate exact solutions describing static and spherically symmetric charged black holes surrounded by a cloud of strings within the framework of bumblebee gravity. We begin by analyzing the thermodynamic properties of these black hole solutions, including their mass, temperature, and entropy, highlighting how Lorentz-violating effects alter standard results. Next, we examine the optical properties of the spacetime, focusing on the photon sphere, the resulting black hole shadow, and the deflection of light, thereby providing potential observational signatures of Lorentz violation. Finally, we explore the impact of Lorentz-violating parameters on classical gravitational tests within the Solar System, such as advance of perihelion precession, in order to set observational constraints. Our analysis provides a comprehensive investigation of the interplay between Lorentz violation, black hole physics, and cloud of strings, offering a framework to probe new physics beyond GR.