Effects of New Viscosity Model on Cosmological Evolution

Abstract

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 astrophysics phenomena. Actually we have not fully understood the physical origin and effects of cosmic viscosity, including its functions for the universe evolution in reality. In this present article we extend the concept of temperature-dependent 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. By considering that a modification of standard model with viscosity named as $\Lambda$CDM-V model is constructed, which is supported by data fitting. In addition to the enhancement to cosmic age value, the $\Lambda$CDM-V model possesses other two pleasing features: the prediction about the no-rip/singularity future and the mechanism of smooth transition from imperfect cosmological models to perfect ones.