Thermodynamics of horizons: de Sitter black holes and reentrant phase transitions

TL;DR

This paper develops a method to analyze the thermodynamics of de Sitter black holes, revealing complex phase structures including reentrant phase transitions, similar to those found in anti-de Sitter black holes.

Contribution

It introduces a new approach to study de Sitter black hole thermodynamics, capturing correlations between horizons and uncovering reentrant phase transitions.

Findings

Reentrant phase transitions in six-dimensional Kerr-dS black holes

Thermodynamics of de Sitter black holes analogous to AdS case

Unified Gibbs free energy-like potential for horizon systems

Abstract

In this paper we propose a straightforward method for understanding the thermodynamics of black holes in de Sitter space, one that will allow us to study these black holes in a way that is analogous to the anti-de Sitter case. As per usual, we formulate separate thermodynamic first laws for each horizon present in the spacetime, and study their thermodynamics as if they were independent systems characterized by their own temperature. That these systems are not entirely independent and various thermodynamic quantities in them are in fact "correlated" is reflected by the fact that their thermodynamics can be captured by a single Gibbs free energy-like thermodynamic potential. This quantity contains information about possible phase transitions in the system and allows us to uncover a rich phase structure for de Sitter black holes. In particular, we discover reentrant phase transitions for Kerr-dS black holes in six dimensions, a phenomenon recently observed for their six dimensional AdS cousins.