On the inner horizon instability of non-singular black holes

TL;DR

This paper reviews the instability of the non-singular core in regular black holes, emphasizing the importance of non-perturbative backreaction effects for understanding their physical viability.

Contribution

It highlights the critical role of non-perturbative backreaction in the instability of regular black hole cores, challenging previous assumptions of stability.

Findings

Non-perturbative backreaction is significant in core instability.

Regular black holes may be inherently unstable due to core dynamics.

Stability analyses must incorporate non-perturbative effects.

Abstract

Regular black holes represent a conservative model in which the classical singularity is replaced by a non-singular core without necessarily modifying the spacetime outside the trapping horizon. Given the possible lack of phenomenological signatures, it is crucial to study the consistency of the model. In this short work, we review the physical mechanism leading to the instability of the central core, arguing that non-perturbative backreaction is non-negligible and must be taken into account to provide a meaningful description of physical black holes.