Temperature Evolution Law of Imperfect Relativistic Fluids

TL;DR

This paper presents a covariant, frame-independent formulation of the temperature evolution law for dissipative relativistic fluids, including effects of gravitational particle creation and viscosity, unifying previous approaches.

Contribution

It generalizes existing theories by deriving a universal temperature variation formula applicable in different frames, incorporating particle creation and viscosity effects.

Findings

Derived a frame-independent temperature evolution formula.

Analyzed the impact of gravitational particle creation.

Unified previous relativistic fluid theories.

Abstract

The first-order general relativistic theory of a generic dissipative (heat-conducting, viscous, particle-creating) fluid is rediscussed from a unified covariant frame-independent point of view. By generalizing some previous works in the literature, we derive a formula for the temperature variation rate, which is valid both in Eckart's (particle) and in the Landau-Lifshitz (energy) frames. Particular attention is paid to the case of gravitational particle creation and its possible cross-effect with the bulk viscosity mechanism.