Ruling out the Modified Chaplygin Gas cosmologies

The Modified Chaplygin Gas (MCG) model belongs to the class of a unified models of dark energy (DE) and dark matter (DM). It is characterized by an equation of state (EoS) pc=Bρ−A/ρα, where the case B=0 corresponds to the Generalized Chaplygin Gas (GCG) model. Using a perturbative analysis and power spectrum observational data we show that the MCG model is not a successful candidate for the cosmic medium unless B=0. In this case, it reduces to the usual GCG model.