Thermodynamics of de Sitter Black Holes with Conformally Coupled Scalar Fields

TL;DR

This paper studies the thermodynamics and phase transitions of de Sitter black holes conformally coupled to scalar fields, revealing Hawking-Page-like transitions influenced by boundary conditions and cosmic censorship bounds.

Contribution

It introduces a detailed thermodynamic analysis of these black holes using a Euclidean action approach, highlighting phase transitions and the role of boundary conditions.

Findings

Hawking-Page-like phase transitions identified in conformally coupled scalar field black holes.

Phase transition behavior depends on boundary conditions and cosmic censorship bounds.

Extended phase space analysis reveals thermodynamic stability and phase structure.

Abstract

We investigate the thermodynamic properties of 3+1 dimensional black holes in asymptotically de Sitter spacetimes, conformally coupled to a real scalar field. We use a Euclidean action approach, where boundary value data is specified at a finite radius `cavity' outside the black hole, working in the extended phase space where the cosmological constant is treated as a thermodynamic pressure. We examine the phase structure of these black holes through their free energy. For the MTZ subclass of solutions, we find Hawking-Page-like phase transitions from a black hole spacetime to thermal de Sitter with a scalar field. In the more general case, Hawking-Page-like phase transitions are also present, whose existence depends further on a particular cosmic censorship bound.