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 $p = - \tilde{A}(a)/\rho^{\alpha}$, where $a$ is the scale factor and $\tilde{A}(a)=-w_XAa^{-3(1+w_X)(1+\alpha)}$. 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 $\alpha$. We discuss the cosmological consequences led by such an unified dark sectors 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.