Eur. Phys. J. C (2007) 52: 223-228
https://doi.org/10.1140/epjc/s10052-007-0357-9

Regular Article - Theoretical Physics

A FRW dark fluid with a non-linear inhomogeneous equation of state

¹ Department of Energy and Process Engineering, Norwegian University of Science and Technology, Kolbj. Hejesv. 2, 7491, Trondheim, Norway
² Facultat de Ciències, Instituto de Ciencias del Espacio (CSIC) and Institut d’Estudis Espacials de Catalunya (IEEC/CSIC) Campus UAB, Torre C5-Parell-2a planta, 08193, Bellaterra (Barcelona), Spain
³ Tomsk State Pedagogical University, Tomsk, Russia

^* e-mail: iver.h.brevik@ntnu.no

Received: 31 May 2007
Published online: 17 July 2007

Abstract

A dark Friedman–Robertson–Walker fluid governed by a non-linear inhomogeneous equation of state is considered that can be viewed as a conveniently simple paradigm for a whole class of models that exhibit phase transitions from a non-phantom towards a phantom era (superacceleration transition). On the other hand, such dark fluid models may also describe quintessence-like cosmic acceleration. Thermodynamical considerations for the processes involved, which are of great importance in the characterization of the global evolution of the corresponding universe, are given too. Connecting the proposed equation of state with an anisotropic Kasner universe with viscosity, we are led to the plausible conjecture of a dark fluid origin of the anisotropies in the early universe.