2011/07/01 by A. Montiel, A Montiel, N. Bretón +1 · 21 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Baryon acoustic oscillations #Consistency (knowledge bases) #Cosmic microwave background #Cosmological constant #Cosmology #Dark energy #Deceleration parameter #Gamma-ray bursts and supernovae #Redshift #Scientific Research and Discoveries #Volume viscosity #astro-ph.CO #hep-th
paper · pdf · doi:10.1088/1475-7516/2011/08/023
published in Journal of Cosmology and Astroparticle Physics 2011(08), 023 (Institute of Physics) · 11 pages, 3 figures, submitted to JCAP
arxiv created 2011/07/01 · openalex publication_date 2011/08/24 · arxiv updated 2011/09/02 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
In this paper we extend the range of consistency of a constant bulk viscosity model to redshifts up to z ∼ 8.1. In this model the dark sector of the cosmic substratum is a viscous fluid with pressure p = −ζθ, where θ is the fluid-expansion scalar and ζ is the coefficient of bulk viscosity. Using the sample of 59 high-redshift GRBs reported by Wei (2010), we calibrate GRBs at low redshifts with the Union 2 sample of SNe Ia, thus avoiding the circularity problem. Testing the constant bulk viscosity model with GRBs we found the best fit for the viscosity parameter in the range 0 < < 3, so that it be consistent with previous probes; we also determined the deceleration parameter q 0 and the redshift of transition to accelerated expansion. Besides, we present an updated analysis of the model with CMB5-year data and CMB7-year data, as well as with the baryon acoustic peak BAO. From the statistics with CMB it turns out that the model does not describe in a feasible way to such a far epoch of recombination of the universe, but is in very good concordance for epochs as far as z ∼ 8.1 till present.