Generalized Chaplygin gas and cosmic microwave background radiation constraints

We study the dependence of the location of the cosmic microwave background radiation peaks on the parameters of the generalized Chaplygin gas model, whose equation of state is given by $p=-A/{\rho }^{\alpha },$ where A is a positive constant and $0<\mathrm{}\alpha <~1.$ We find, in particular, that observational data arising from Archeops, BOOMERANG, supernova and high-redshift observations allow constraining significantly the parameter space of the model. Our analysis indicates that the emerging model is clearly distinguishable from the $\alpha =1\mathrm{}$ Chaplygin case and the $\Lambda \mathrm{CDM}$ model.