# Probing bulk viscous matter-dominated models with gamma-ray bursts

## Abstract

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 ζ-tilde in the range 0 < ζ-tilde < 3, so that it be consistent with previous probes; we also determined the deceleration parameter q{sub 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 ∼more »

- Authors:

- Dpto. de Física, Centro de Investigación y de Estudios Avanzados del I. P. N., Av. IPN 2508, D.F. (Mexico)

- Publication Date:

- OSTI Identifier:
- 22277812

- Resource Type:
- Journal Article

- Journal Name:
- Journal of Cosmology and Astroparticle Physics

- Additional Journal Information:
- Journal Volume: 2011; Journal Issue: 08; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1475-7516

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; BARYONS; COSMOLOGICAL MODELS; COSMOLOGY; PROBES; RECOMBINATION; RED SHIFT; SCALARS; SUPERNOVAE; UNIVERSE; VISCOSITY

### Citation Formats

```
Montiel, A., and Bretón, N., E-mail: amontiel@fis.cinvestav.mx, E-mail: nora@fis.cinvestav.mx.
```*Probing bulk viscous matter-dominated models with gamma-ray bursts*. United States: N. p., 2011.
Web. doi:10.1088/1475-7516/2011/08/023.

```
Montiel, A., & Bretón, N., E-mail: amontiel@fis.cinvestav.mx, E-mail: nora@fis.cinvestav.mx.
```*Probing bulk viscous matter-dominated models with gamma-ray bursts*. United States. doi:10.1088/1475-7516/2011/08/023.

```
Montiel, A., and Bretón, N., E-mail: amontiel@fis.cinvestav.mx, E-mail: nora@fis.cinvestav.mx. Mon .
"Probing bulk viscous matter-dominated models with gamma-ray bursts". United States. doi:10.1088/1475-7516/2011/08/023.
```

```
@article{osti_22277812,
```

title = {Probing bulk viscous matter-dominated models with gamma-ray bursts},

author = {Montiel, A. and Bretón, N., E-mail: amontiel@fis.cinvestav.mx, E-mail: nora@fis.cinvestav.mx},

abstractNote = {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 ζ-tilde in the range 0 < ζ-tilde < 3, so that it be consistent with previous probes; we also determined the deceleration parameter q{sub 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.},

doi = {10.1088/1475-7516/2011/08/023},

journal = {Journal of Cosmology and Astroparticle Physics},

issn = {1475-7516},

number = 08,

volume = 2011,

place = {United States},

year = {2011},

month = {8}

}