Extended phase space thermodynamics for Lovelock black holes with non-maximally symmetric horizons

TL;DR

This paper explores the thermodynamics and phase transitions of higher-dimensional Lovelock black holes with non-maximally symmetric horizons, revealing unique critical behaviors and phase phenomena not seen in Einstein or Lovelock gravity.

Contribution

It introduces the study of thermodynamics for Lovelock black holes with non-constant curvature horizons, uncovering novel critical behaviors and phase transitions across various dimensions.

Findings

Ricci flat black holes with nonconstant curvature horizons show critical behavior.

Multiple phase transitions including first-order, reentrant, and zeroth-order are observed.

Three critical points can exist for certain parameters with negative curvature horizons.

Abstract

We study thermodynamics and critical behaviors of higher-dimensional Lovelock black holes with non-maximally symmetric horizons in the canonical ensemble of extended phase space. The effects from non-constancy of the horizon of the black hole via appearing two chargelike parameters in thermodynamic quantities of third-order Lovelock black holes are investigated. We find that Ricci flat black holes with nonconstant curvature horizon show critical behavior. This is an interesting feature that is not seen for any kind of black hole in Einstein or Lovelock gravity in the literature. We examine how various interesting thermodynamic phenomena such as standard first-order small-large black hole phase transition, a reentrant phase transition, or zeroth order phase transition happens for Ricci flat, spherical, or hyperbolic black holes with nonconstant curvature horizon depending on the values of Lovelock coefficient and chargelike parameters. While for a spherical black hole of third order Lovelock gravity with constant curvature horizon phase transition is observed only for $7\leq d \leq11$, for our solution criticality and phase transition exist in every dimension. With a proper choice of the free parameters, a large-small-large black hole phase transition occurs. This process is accompanied by a finite jump of the Gibbs free energy referred to as a zeroth-order phase transition. For the case $\kappa=-1$ a novel behavior is found for which three critical points could exist.