Stability and topological nature of charged Gauss-Bonnet AdS black holes in five dimensions

TL;DR

This paper explores the topological and thermodynamic properties of charged Gauss-Bonnet AdS black holes in five dimensions, revealing how the Gauss-Bonnet coupling influences phase transitions and stability in different horizon geometries.

Contribution

It introduces a topological approach to black hole thermodynamics, showing how Gauss-Bonnet coupling affects the classification and phase structure of charged AdS black holes.

Findings

Gauss-Bonnet coupling alters topological classification of black holes.

Topological analysis indicates liquid-gas phase transitions for k=+1.

Global analysis reveals Hawking-Page transitions and stable black hole branches.

Abstract

We investigate the thermodynamics of Reissner-Nordstrom Gauss-Bonnet (RN-GB) black holes in anti-de Sitter (AdS) space with three horizon geometries (k=+1,0,-1) within the grand canonical ensemble. Using the recently developed topological approach to black hole thermodynamics, inspired by Duan's $\phi$-mapping theory, we analyze the black holes by treating both critical points in the phase diagram and black hole solutions as defects in the thermodynamic parameter space. Our results show that the Gauss-Bonnet coupling significantly alters the topological classification of RN-GB AdS black holes, distinguishing them from their RN AdS counterparts in the grand canonical ensemble, while aligning with their canonical ensemble counterparts. Complementary analyses of local stability using specific heat validate the implication of topological analysis. Furthermore, an evaluation of global stability via Gibbs free energy provides a comprehensive understanding on the system's phase structure. Notably, for k=+1, topological analysis suggests liquid-gas type phase transitions, whereas global analysis favors Hawking-Page transitions. For k=-1, topology indicates a single stable black hole branch, yet the global analysis reveals the presence of Hawking-Page transition.