Constraining a matterdominated cosmological model with bulk viscosity proportional to the Hubble parameter
Abstract
We present and constrain a cosmological model where the only component is a pressureless fluid with bulk viscosity as an explanation for the present accelerated expansion of the universe. We study the particular model of a bulk viscosity coefficient proportional to the Hubble parameter: ζm = ζH, where ζ = constant. The possible values of ζ are constrained using the SNe Ia Gold 2006 sample, the CMB shift parameter R from the threeyear WMAP observations, the Baryon Acoustic Oscillation (BAO) peak A from the Sloan Digital Sky Survey (SDSS) and the Second Law of Thermodynamics (SLT). It was found that this model is in agreement with the SLT using only the SNe Ia test. However when the model is submitted to the three cosmological tests together (SNe+CMB+BAO) the results are: 1.the model violates the SLT, 2.It predicts a value of H_{0}~53 km.sec^{1}.Mpc^{1} for the Hubble constant, and 3.we obtain a bad fit to data with a χmin^{2}~532 (χd.o.f.^{2}~2.92). These results indicate that this model is viable just if the bulk viscosity is triggered in recent times.
 Publication:

Gravitation and Cosmology
 Pub Date:
 December 2008
 DOI:
 10.1063/1.3058568
 arXiv:
 arXiv:0810.0303
 Bibcode:
 2008AIPC.1083....1A
 Keywords:

 98.80.k;
 66.20.d;
 95.36.+x;
 97.60.Bw;
 Cosmology;
 Viscosity of liquids;
 diffusive momentum transport;
 Dark energy;
 Supernovae;
 General Relativity and Quantum Cosmology;
 Astrophysics
 EPrint:
 5 pages, 2 eps figures. Work presented in the III International Meeting on Gravitation and Cosmology, Morelia, Mexico, May 2630, 2008. Submitted to AIP Conference Proceedings of this conference. Related work: arXiv:0801.1686