Loop Quantum Gravity motivated multihorizon rotating black holes

TL;DR

This paper constructs a new class of rotating black hole models inspired by loop quantum gravity, revealing diverse horizon structures and extending the understanding of quantum-corrected black holes beyond non-rotating cases.

Contribution

It introduces LQG-motivated rotating black holes using a revised Newman-Janis algorithm, filling a gap in quantum gravity models for rotating black holes.

Findings

Existence of black holes with multiple horizons and no horizons depending on parameters

Extremal black holes with angular momentum exceeding mass for non-zero LQG parameter

Rich spacetime structures influenced by quantum corrections

Abstract

With a semiclassical polymerization in the loop quantum gravity (LQG), the interior of Schwarzschild black holes provides a captivating single-horizon regular black hole spacetime. The shortage of rotating black hole models in loop quantum gravity (LQG) substantially restrains the progress of testing LQG from observations. Motivated by this, starting with a spherical LQG black hole as a seed metric, we construct a rotating spacetime using the revised Newman-Janis algorithm, namely, the LQG-motivated rotating black holes (LMRBH), which encompasses Kerr ($l=0$) black holes as an exceptional case. We discover that for any random $l>0$, unlike Kerr black hole, an extremal LMRBH refers to a black hole with angular momentum $a>M$. The rotating metric, in parameter space, describes (1) black holes with an event and Cauchy horizons, (2) black holes with three horizons, (3) black holes with only one horizon or (4) no horizon spacetime. We also discuss the horizon and global structure of the LMRBH spacetimes and its dependence on $l/M$ that exhibits rich spacetime structures in the ($M,\;a,\;l$) parameter space.