Qualitative Analysis of Causal Cosmological Models

TL;DR

This paper analyzes causal cosmological models with dissipative fluids using dynamical systems, revealing stability conditions for different cosmological constants and exploring the effects of various equations of state.

Contribution

It provides a novel qualitative analysis of Friedmann-Robertson-Walker universes with dissipative fluids, considering both truncated and non-truncated causal transport equations, with new phase space and equation of state assumptions.

Findings

De Sitter expansion can satisfy hydrodynamic and non-thermalizing conditions simultaneously.

For zero cosmological constant, expansions are stable if a fluid parameter is below 1/2.

The case with positive cosmological constant is analyzed in detail.

Abstract

The Einstein's field equations of Friedmann-Robertson-Walker universes filled with a dissipative fluid described by both the {\em truncated} and {\em non-truncated} causal transport equations are analyzed using techniques from dynamical systems theory. The equations of state, as well as the phase space, are different from those used in the recent literature. In the de Sitter expansion both the hydrodynamic approximation and the non-thermalizing condition can be fulfilled simultaneously. For $\Lambda=0$ these expansions turn out to be stable provided a certain parameter of the fluid is lower than 1/2. The more general case $\Lambda>0$ is studied in detail as well.