Inhomogeneous viscous fluids in FRW universe

TL;DR

This paper reviews inhomogeneous viscous fluids in a flat FRW universe, exploring their potential to cause future singularities like the Big Rip and how coupling with dark matter can prevent such outcomes.

Contribution

It investigates the effects of fluid-dark matter coupling in a de Sitter universe, showing how it can solve the coincidence problem and prevent Big Rip singularities.

Findings

Coupling fluids with dark matter can stabilize de Sitter solutions.

Fluid models may lead to future singularities like Big Rip.

Coupling can solve the coincidence problem.

Abstract

We give a brief review of some aspects of inhomogeneous viscous fluids in a flat Friedmann-Robertson-Walker Universe. In general, it is pointed out that several fluid models may bring the future Universe evolution to become singular, with the appearance of the so-called Big Rip scenario. We investigate the effects of fluids coupled with dark matter in a de Sitter Universe, by considering several cases. Due to this coupling, the coincidence problem may be solved, and if the de Sitter solution is stable, the model is also protected against the Big Rip singularity.