Rotating black hole in Rastall theory

TL;DR

This paper derives and analyzes rotating black hole solutions in Rastall gravity, exploring their properties, thermodynamics, and particle dynamics, thus providing a new framework to test modified gravity theories through astrophysical observations.

Contribution

It introduces the rotating Rastall black hole solution, generalizing Kerr-Newman black holes within Rastall gravity and analyzing their horizons, thermodynamics, and particle motion.

Findings

Existence of a critical rotation parameter for extremal black holes.

Presence of non-extremal black holes with Cauchy and event horizons.

No black hole solutions beyond the critical rotation parameter.

Abstract

Rotating black hole solutions in theories of modified gravity are important as they offer an arena to test these theories through astrophysical observation. The non-rotating black hole can be hardly tested since the black hole spin is very important in any astrophysical process. We present rotating counterpart of a recently obtained spherically symmetric exact black hole solution surrounded by perfect fluid in the context of Rastall theory, viz, rotating Rastall black hole that generalize the Kerr-Newman black hole solution. In turn, we analyze the specific cases of the Kerr-Newman black holes surrounded by matter like dust and quintessence fields. Interestingly, for a set of parameters and a chosen surrounding field, there exists a critical rotation parameter ($a=a_{E}$), which corresponds to an extremal black hole with degenerate horizons, while for $a<a_{E}$, it describes a non-extremal black hole with Cauchy and event horizons, and no black hole for $a>a_{E}$ with value $a_E$ is also influenced by these parameters. We also discuss the thermodynamical quantities associated with rotating Rastall black hole, and analyze the particle motion with the behavior of effective potential.