1303.4964 (Jiaxin Wang et al.)
Jiaxin Wang, Xinhe Meng
Bulk viscosity has been intrinsically existing in the observational cosmos evolution with various effects for different cosmological evolution stages endowed with complicated cosmic media. Normally in the idealized "standard cosmology" the physical viscosity effect is often negligent in some extent by assumptions, except for galaxies formation and evolution or the like astro-physics phenomena. Actually we have not fully understood the physical origin and effects of cosmic viscosity, including its practical functions for the universe evolution in reality. In this present article we extend the concept of temperature related viscosity from classical statistical physics to observational cosmology, especially we examine the cosmological effects with possibility of the existence for two kinds of viscosity forms, which are described by the Chapman's relation and Sutherland's formula respectively. With that the unified dark fluid model and also a modification of standard model with viscosity which is named as $\Lambda$CDM-V model are constructed physically. While the unified dark fluid model constrained by observational data is closely related with bouncing phenomenon, the $\Lambda$CDM-V model is supported more by data-sets fittings with results indicating that temperature related viscosity could not totally explain the rich physics of dark energy phenomena. In addition to the enhancement to cosmic age value, the $\Lambda$CDM-V model possesses another two pleasing features: the prediction about the no-rip/singularity future and the mechanism of smooth transition from imperfect cosmological models to perfect ones.
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http://arxiv.org/abs/1303.4964
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