https://doi.org/10.1140/epjc/s10052-012-2053-7
Regular Article - Theoretical Physics
Rip/singularity free cosmology models with bulk viscosity
1
Department of Physics, Nankai University, Tianjin, 300071, China
2
Kavli Institute of Theoretical Physics China, CAS, Beijing, 100190, China
* e-mail: mazhiyuan@mail.nankai.edu.cn
Received:
22
February
2012
Revised:
15
April
2012
Published online:
13
July
2012
In this paper we present two concrete models of non-perfect fluid with bulk viscosity to interpret the observed cosmic accelerating expansion phenomena, avoiding the introduction of exotic dark energy. The first model we inspect has a viscosity of the form ζ=ζ 0+(ζ 1−ζ 2 q)H by taking into account the decelerating parameter q, and the other model is of the form ζ=ζ 0+ζ 1 H+ζ 2 H 2. We give the exact solutions of such models and further constrain them with the latest Union2 data as well as the currently observed Hubble-parameter dataset (OHD). Then we discuss the fate of universe evolution in these models, which confronts neither future singularity nor little/pseudo rip. From the resulting curves by best-fittings we find a much more flexible evolution processing due to the presence of viscosity while being consistent with the observational data in the region of data fitting. With the bulk viscosity considered, a more realistic universe scenario is characterized comparable with the ΛCDM model but without introducing the mysterious dark energy.
© Springer-Verlag / Società Italiana di Fisica, 2012