Stability of degenerate Cauchy horizons in black hole spacetimes

TL;DR

This paper investigates the stability of degenerate Cauchy horizons in multihorizon black hole spacetimes, finding classical stability but quantum instability regardless of the asymptotic spacetime behavior.

Contribution

It provides a detailed analysis of the classical and quantum stability of degenerate Cauchy horizons across different asymptotic geometries.

Findings

Cauchy horizons are classically stable in these spacetimes.

Quantum effects cause instability of the horizons.

Stability results are consistent across flat, anti-de Sitter, and de Sitter backgrounds.

Abstract

In the multihorizon black hole spacetimes, it is possible that there are degenerate Cauchy horizons with vanishing surface gravities. We investigate the stability of the degenerate Cauchy horizon in black hole spacetimes. Despite the asymptotic behavior of spacetimes (flat, anti-de Sitter, or de Sitter), we find that the Cauchy horizon is stable against the classical perturbations, but unstable quantum mechanically.