Insight into the Microscopic Structure of an AdS Black Hole from Thermodynamical Phase Transition

TL;DR

This paper explores the microscopic structure of charged AdS black holes by analyzing thermodynamic phase transitions, revealing changes in molecule density, latent heat, and interactions, which offer new insights into black hole microphysics.

Contribution

It introduces the concept of black hole molecule number density and links thermodynamic phase behavior to microscopic interactions, providing novel understanding of black hole microstructure.

Findings

Number density changes abruptly at the phase transition.

Latent heat is associated with the change in number density.

Thermodynamic scalar curvature indicates weak attractive interactions.

Abstract

Comparing with an ordinary thermodynamic system, we investigate the possible microscopic structure of a charged anti-de Sitter black hole completely from the thermodynamic viewpoint. The number density of the black hole molecules is introduced to measure the microscopic degrees of freedom of the black hole. We found that the number density suffers a sudden change accompanied by a latent heat when the black hole system crosses the small-large black hole coexistence curve, while when the system passes the critical point, it encounters a second-order phase transition with a vanishing latent heat due to the continuous change of the number density. Moreover, the thermodynamic scalar curvature suggests that there is a weak attractive interaction between two black hole molecules. These phenomena might cast new insight into the underlying microscopic structure of a charged anti-de Sitter black hole.