Universal criterion for black hole stability

TL;DR

This paper establishes a universal criterion for black hole stability in thermal equilibrium, linking mass, horizon area, and entropy without relying on specific spacetime models.

Contribution

It introduces a general stability criterion based solely on the relationship between mass, horizon area, and entropy for large black holes.

Findings

Large black holes can be stable if mass exceeds microcanonical entropy.

Stability criterion is independent of specific classical spacetime properties.

Analysis applies to non-rotating black holes in thermal equilibrium.

Abstract

It is shown that a non-rotating macroscopic black hole with very large horizon area can remain in stable thermal equilibrium with Hawking radiation provided {\it its mass, as a function of horizon area, exceeds its microcanonical entropy, i.e., its entropy when isolated, without thermal radiation or accretion, and having a constant horizon area} (in appropriate units). The analysis does not use properties of specific classical spacetimes, but depends only on the plausible assumption that the mass is a function of the horizon area for large areas.