Constraints on the generalized tachyon field models from latest observational data

Abstract

We consider constraints on generalized tachyon field (GTF) models from latest observational data (including 182 gold SNIa data, the shift parameter, and the acoustic scale). We obtain at 68.3% confidence level Ωm = 0.37 ± 0.01, k0 = 0.09−0.03+0.04, α = 1.8−0.7+7.4 (the best fit values of the parameters) and zq = 0∼0.47−0.51 (the transitional redshift) for GTF as the dark energy component only; k0 = 0.21−0.18+0.20, α = 0.57 ± 0.01 and zq = 0∼0.49–0.68 for GTF as the unification of dark energy and dark matter. In both cases, GTF evolves like dark matter in the early universe. By applying model-comparison statistics and testing with independent H(z) data, we find that the GTF dark energy scenario is favored over the ΛCDM model, and the ΛCDM model is favored over GTF unified dark matter by the combined data. For GTF as the dark energy component, the fluctuations of matter density are consistent with the growth of linear density perturbations. For GTF unified dark matter, the growth of GTF density fluctuations goes more slowly for , meaning that GTF does not behave as classical ΛCDM scenarios.

Locations

• Journal of Cosmology and Astroparticle Physics - View
• arXiv (Cornell University) - View - PDF
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