Dark Energy and Viscous Cosmology

TL;DR

This paper explores how bulk viscosity in dark energy models can lead to phantom behavior, potentially causing future singularities in a flat FRW universe, expanding understanding of cosmic fluid dynamics.

Contribution

It introduces a model where bulk viscosity proportional to scalar expansion drives the universe into the phantom regime, even from quintessence-like conditions.

Findings

Bulk viscosity can induce phantom behavior in dark energy models.

Viscous effects may lead to future singularities in the universe.

Viscosity proportional to scalar expansion influences cosmic evolution.

Abstract

Singularities in the dark energy universe are discussed, assuming that there is a bulk viscosity in the cosmic fluid. In particular, it is shown how the physically natural assumption of letting the bulk viscosity be proportional to the scalar expansion in a spatially flat FRW universe can drive the fluid into the phantom region (w < -1), even if lies in the quintessence region (w > -1) in the non-viscous case.