Isotropic AdS/CFT fireball

TL;DR

This paper explores the thermodynamics of isotropic AdS/CFT fireballs, analyzing their behavior in various cosmological backgrounds and identifying a Casimir-like energy contribution related to black hole formation thresholds.

Contribution

It provides a detailed holographic analysis of isotropic AdS/CFT fireballs in different cosmological settings, including the role of Casimir-like terms and conditions for local thermal equilibrium.

Findings

Boundary matter satisfies the first law of thermodynamics across all conditions.

A Casimir-type energy term varies with spatial curvature parameter k.

The fluid is scale-invariant and in local thermal equilibrium only under certain temperature conditions.

Abstract

We study the AdS/CFT thermodynamics of the spatially isotropic counterpart of the Bjorken similarity flow in d-dimensional Minkowski space with d>=3, and of its generalisation to linearly expanding d-dimensional Friedmann-Robertson-Walker cosmologies with arbitrary values of the spatial curvature parameter k. The bulk solution is a nonstatic foliation of the generalised Schwarzschild-AdS black hole with a horizon of constant curvature k. The boundary matter is an expanding perfect fluid that satisfies the first law of thermodynamics for all values of the temperature and the spatial curvature, but it admits a description as a scale-invariant fluid in local thermal equilibrium only when the inverse Hawking temperature is negligible compared with the spatial curvature length scale. A Casimir-type term in the holographic energy-momentum tensor is identified from the threshold of black hole formation and is shown to take different forms for k>=0 and k<0.