Constraints on modified Chaplygin gas from recent observations and a comparison of its status with other models

TL;DR

This paper constrains the modified Chaplygin gas model using recent cosmological observations, showing it fits data well and crosses the phantom divide, with parameters favoring a dark energy-dark matter unification.

Contribution

It provides the first comprehensive observational constraints on the MCG model and compares its performance with other dark energy models using multiple data sets.

Findings

Best-fit parameters: B=-0.085, B_s=0.822, α=1.724

The equation of state w(z) crosses -1 in the past and present

MCG has the smallest chi-squared value among tested models

Abstract

In this Letter, a modified Chaplygin gas (MCG) model of unifying dark energy and dark matter with the exotic equation of state $p_{MCG}=B\rho_{MCG} -\frac A{\rho_{MCG}^\alpha}$ 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 ($B$,$B_{s}$,$\alpha$) 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 $1\sigma$ confidence level of $w(0)$ is $-0.946\leq w(0)\leq-1.282$. Finally, we find that the MCG model has the smallest $\chi^{2}_{min}$ 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.