Dynamics of Relativistic Interacting Gases : from a Kinetic to a Fluid Description

TL;DR

This paper develops a covariant kinetic formalism for interacting gases, bridging microscopic interactions and macroscopic fluid descriptions, with applications in cosmology and structure formation.

Contribution

It introduces a covariant framework for describing interacting gases from microscopic collision models to macroscopic fluid equations.

Findings

Provides a collision term model for relativistic gases.

Derives effective macroscopic fluid equations from microscopic dynamics.

Applicable to cosmology and structure formation studies.

Abstract

Starting from a microscopic approach, we develop a covariant formalism to describe a set of interacting gases. For that purpose, we model the collision term entering the Boltzmann equation for a class of interactions and then integrate this equation to obtain an effective macroscopic description. This formalism will be useful to study the cosmic microwave background non-perturbatively in inhomogeneous cosmologies. It should also be useful for the study of the dynamics of the early universe and can be applied, if one considers fluids of galaxies, to the study of structure formation.