Modified Chaplygin Gas as a Unified Dark Matter and Dark Energy Model and Cosmic Constraints

TL;DR

This paper constrains a modified Chaplygin gas model as a unified dark matter and dark energy candidate using current cosmic observational data, finding tight parameter bounds through MCMC analysis.

Contribution

It treats the modified Chaplygin gas as a single unified dark sector without separating into dark matter and dark energy, which is a novel approach.

Findings

Tight constraints on model parameters using observational data.

Unified dark sector model fits current cosmological observations.

Parameter values are consistent with a unified dark matter and dark energy scenario.

Abstract

A modified Chaplygin gas model (MCG), $\rho_{MCG}/\rho_{MCG0}=[B_{s}+(1-B_{s})a^{-3(1+B)(1+\alpha)}]^{1/(1+\alpha)}$, as a unified dark matter model and dark energy model is constrained by using current available cosmic observational data points which include type Ia supernovae, baryon acoustic oscillation and the seventh year full WMAP data points. As a contrast to the consideration in the literatures, we {\it do not} separate the MCG into two components, i.e. dark mater and dark energy component, but we take it as a whole energy component-a unified dark sector. By using Markov Chain Monte Carlo method, a tight constraint is obtained: $\alpha= 0.000727_{- 0.00140- 0.00234}^{+ 0.00142+ 0.00391}$, $B=0.000777_{- 0.000302- 0.000697}^{+ 0.000201+ 0.000915}$ and $B_s= 0.782_{- 0.0162- 0.0329}^{+ 0.0163+ 0.0307}$ .}