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

We propose a new model for the description of unification of dark energy and dark matter, dubbed new generalized Chaplygin gas (NGCG) model. We study the cosmological scenario arising from the dynamics of this new generalized Chaplygin gas. The equation of state of the system is given by p = - A(a)/\ρ\α, where a is the scale factor and 0 < \α \≤ 1, and A(a)=-wXAa-3(1+wX)(1+\α). We show that the cosmological picture which this model describes is an interacting XCDM system, in which dark matter decays to dark energy. From this scenario, the origin of the "intermediate regime" (p=-wX\α\ρ) is clarified and the production mechanism of the acoustics is illustrated.