Survival of the black hole's Cauchy horizon under non-compact perturbations

TL;DR

This paper numerically investigates the internal structure of a charged black hole under non-compact perturbations, revealing that part of the Cauchy horizon persists as a null singularity, challenging previous expectations of its destruction.

Contribution

It demonstrates through numerical simulation that non-compact support perturbations can leave the Cauchy horizon partially intact as a null singularity in a simplified black hole model.

Findings

Cauchy horizon survives as a null singularity under certain perturbations

Logarithmic growth of scalar field influences horizon stability

Partial preservation of internal black hole structure

Abstract

We study numerically the evolution of spactime, and in particular of a spacetime singularity, inside a black hole under a class of perturbations of non-compact support. We use a very simplified toy model of a spherical charged black hole which is perturbed nonlinearly by a self-gravitating, spherical scalar field. The latter grows logarithmically with advanced time along an outgoing characteristic hypersurface. We find that for that class of perturbations a portion of the Cauchy horizon survives as a non-central, null singularity.