Structure of the Spherical Black Hole Interior

TL;DR

This paper investigates the internal structure of charged spherical black holes, demonstrating through an approximate analytic solution that a mass inflation singularity exists at the Cauchy horizon without evidence of a preceding spacelike singularity.

Contribution

It provides an analytic approach confirming the presence of a mass inflation singularity at the Cauchy horizon in charged black holes, challenging previous numerical suggestions.

Findings

Mass inflation singularity exists at the Cauchy horizon.

No evidence of a spacelike singularity before the Cauchy horizon.

Analytic solution supports the mass inflation scenario.

Abstract

The internal structure of a charged spherical black hole is still a topic of debate. In a nonrotating but aspherical gravitational collapse to form a spherical charged black hole, the backscattered gravitational wave tails enter the black hole and are blueshifted at the Cauchy horizon. This has a catastrophic effect if combined with an outflux crossing the Cauchy horizon: a singularity develops at the Cauchy horizon and the effective mass inflates. Recently a numerical study of a massless scalar field in the \RN background suggested that a spacelike singularity may form before the Cauchy horizon forms. We will show that there exists an approximate analytic solution of the scalar field equations which allows the mass inflation singularity at the Cauchy horizon to exist. In particular, we see no evidence that the Cauchy horizon is preceded by a spacelike singularity.