In this Letter, a modified Chaplygin gas (MCG) model of unifying dark energy and dark matter with the exotic equation of state pMCG = BρMCG− A ρ α M CG is constrained from recently observed data:the 182 Gold SNe Ia, the 3-year WMAP and the SDSS baryon acoustic peak. It is shown that the best fit value of the three parameters (B,Bs,α) in MCG model are (-0.085,0.822,1.724). Furthermore, we find the best fit w(z) crosses -1 in the past and the present best fit value w(0) = −1.114 < −1, and the 1σ confidence level of w(0) is −0.946 ≤ w(0) ≤ −1.282. Finally, we find that the MCG model has the smallest χ 2 min value in all eight given models. According to the Alaike Information Criterion (AIC) of model selection, we conclude that recent observational data support the MCG model as well as other popular models.
In this paper, the 1σ confidence level of transition redshift and present deceleration parameter are studied using modified Chaplygin gas (MCG) model from recent observations: the 182 Gold SNe Ia, three-year WMAP, SDSS baryon acoustic peak and X-ray gas mass fraction in clusters. Concretely, the best fit values of the transition redshift and present deceleration parameter with the 1σ confidence level are [Formula: see text] and [Formula: see text], which indicate the best fit values of zT and q0 for MCG case are surprisingly close to the central values given by Refs. 20 and 21. Furthermore, we plot the evolution of cosmological quantities from MCG model by using the best-fit parameters given by combining constraint, and compare them with ΛCDM model.
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