Observational constraint on generalized Chaplygin gas model

TL;DR

This paper uses recent observational data to constrain the parameters of the generalized Chaplygin gas model, which unifies dark matter and dark energy, finding best-fit values and the evolution of the dark energy equation of state.

Contribution

It provides updated observational constraints on the GCG model parameters and characterizes the dark energy equation of state evolution.

Findings

Best-fit GCG parameters: A_s=0.73, α=-0.09

Dark energy EOS current value: w_0de=-0.96

EOS evolution similar to quiessence

Abstract

We investigate observational constraints on the generalized Chaplygin gas (GCG) model as the unification of dark matter and dark energy from the latest observational data: the Union SNe Ia data, the observational Hubble data, the SDSS baryon acoustic peak and the five-year WMAP shift parameter. It is obtained that the best fit values of the GCG model parameters with their confidence level are $A_{s}=0.73^{+0.06}_{-0.06}$ ($1\sigma$) $^{+0.09}_{-0.09}$ $(2\sigma)$, $\alpha=-0.09^{+0.15}_{-0.12}$ ($1\sigma$) $^{+0.26}_{-0.19}$ $(2\sigma)$. Furthermore in this model, we can see that the evolution of equation of state (EOS) for dark energy is similar to quiessence, and its current best-fit value is $w_{0de}=-0.96$ with the $1\sigma$ confidence level $-0.91\geq w_{0de}\geq-1.00$.