New generalized Chaplygin gas as a scheme for unification of dark energy and dark matter

We propose in this paper a new model for describing the unification of dark energy and dark matter. This new model is a further generalization of the generalized Chaplygin gas (GCG) model, thus dubbed new generalized Chaplygin gas (NGCG) model. The equation of state of the NGCG is given by p = - Ã( a )/ρ α , where a is the scale factor and Ã( a ) = - w X Aa - 3(1 + w X )(1 + α) . We show that the NGCG model is totally dual to an interacting XCDM parametrization scenario, in which the interaction between dark energy and dark matter is characterized by the constant α. We discuss the cosmological consequences led by such a unified dark sector model. Furthermore, we perform a statefinder analysis on this scenario and show the discrimination between this scenario and other dark energy models. Finally, a combined analysis of the data of type Ia supernovae, cosmic microwave background, and large scale structure provides a fairly tight constraint on the parameters of the NGCG model.