Properties of dynamical regular black holes in semiclassical gravity

TL;DR

This paper explores the properties and evolution of regular black holes in semiclassical gravity, highlighting quantum effects near horizons, entropy corrections, and violations of the null energy condition during evaporation.

Contribution

It provides a comprehensive analysis of the thermodynamics, entropy corrections, and dynamical behavior of regular black holes considering quantum effects and backreaction.

Findings

1-loop entropy corrections depend on regularization scheme

Null energy condition is violated near the outer horizon

Quantum effects dominate near the outer apparent horizon during evaporation

Abstract

Regular black holes have become a popular alternative to the singular mathematical black holes predicted by general relativity as they circumvent mathematical pathologies associated with the singularity while preserving crucial black hole features such as the trapping of light. Based on the assumption that semiclassical gravity is valid in the vicinity of their apparent horizons, we review their thermodynamic properties in static scenarios and demonstrate that 1-loop corrections to the Bekenstein-Hawking entropy, accounting for the entanglement entropy of fields, depend on the regularization scheme used. Taking backreaction effects into consideration, we investigate their full dynamical evolution and we examine the behavior of the null energy condition. We find that it is always violated in the vicinity of the outer horizon while being satisfied in the vicinity of the inner horizon, which implies that the trapped spacetime region, as determined from the behavior of null geodesic congruences, is effectively separated into a null energy condition-violating and a non-violating domain. Our findings suggest that quantum effects are more dominant close to the outer apparent horizon and become more pronounced towards the final stages of the evaporation process.