The bigravity black hole and its thermodynamics

TL;DR

This paper examines black hole solutions in bigravity, showing that certain potentials lead to singular horizons while more general potentials admit regular black holes with interesting thermodynamic phase transitions.

Contribution

It demonstrates that the regularity of black hole horizons in bigravity depends on the potential chosen and explores the thermodynamics and phase structure of these solutions.

Findings

Singular horizons occur for specific potentials in bigravity.

More general potentials allow for regular black hole solutions.

Phase transitions are identified at certain critical temperatures.

Abstract

We argue that the Isham-Storey exact solution to bigravity does not describe black holes because the horizon is a singular surface. However, this is not a generic property of bigravity, but a property of a particular potential. More general potentials do accept regular black holes. For regular black holes, we compute the total energy and thermodynamical parameters. Phase transitions occur for certain critical temperatures. We also find a novel region on phase space describing up to 4 allowed states for a given temperature.