Dyonic Taub-NUT-AdS Black Branes: Thermodynamics and Phase Diagrams

TL;DR

This paper explores the thermodynamic phase structure of dyonic Taub-NUT-AdS black branes, revealing complex phase diagrams with multiple critical points and phase transitions influenced by an arbitrary parameter, expanding understanding of these solutions.

Contribution

It introduces a broader class of charges satisfying the first law of thermodynamics, dependent on an arbitrary parameter, and analyzes the resulting complex phase diagrams in various ensembles.

Findings

Existence of multiple critical points depending on parameters.

Identification of first-order phase transitions ending at critical points.

Phase diagrams showing borders of big and small black hole phases.

Abstract

Motivated by the recent developments in the thermodynamics of Taub-NUT spaces and the absence of Misner strings in Taub-NUT solutions with flat horizons, we investigated the phase structure of dyonic Taub-NUT solutions. We follow the treatment proposed in arXiv:2206.09124 and arXiv:2304.06705 to introduce the nut parameter as a conserved charge to the first law. Although the calculated quantities satisfy the first law, we have found a larger class of charges that satisfy the first law and depend on some arbitrary parameter which we call $\alpha$. We choose to describe phase diagrams as NUT parameter-Temperature graphs to show borders of big and small black hole phases. We study the phase structure of these spaces in a mixed ensemble (i.e., we fix the electric potential, the nut parameter, and the magnetic charge), which we classify into different cases depending on the value of $\alpha$. In some of these cases we have first-order phase transitions that end with critical points. These classes could include up to four critical points, again, depending on $\alpha$ and the other quantities.