Qualitative Analysis of Causal Cosmological Models

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 $Λ=0$ these expansions turn out to be stable provided a certain parameter of the fluid is lower than 1/2. The more general case $Λ>0$ is studied in detail as well.