Modified Chaplygin gas as a unified dark matter and dark energy model and cosmic constraints

摘要

A modified Chaplygin gas model (MCG), ρ _MCG/ρ _MCG0=[B _s +(1−B _s )a −3(1+B)(1+α)]1/(1+α), 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 7-year full WMAP data points. As a contrast to the consideration in the literature, we 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 a Markov Chain Monte Carlo method, a tight constraint is obtained: a = 0.000727_{- 0.00140- 0.00234}+ 0.00142+ 0.00391alpha= 0.000727_{- 0.00140- 0.00234}^{+ 0.00142+ 0.00391}, B=0.000777_{- 0.000302- 0.000697}+ 0.000201+ 0.000915B=0.000777_{- 0.000302- 0.000697}^{+ 0.000201+ 0.000915} and B_s = 0.782_{- 0.0162- 0.0329}+ 0.0163+ 0.0307B_{s}= 0.782_{- 0.0162- 0.0329}^{+ 0.0163+ 0.0307}.