Latest Supernova data in the framework of Generalized Chaplygin Gas model

Abstract

We use the most recent Type-Ia Supernova data in order to study the dark energy - dark matter unification approach in the context of the Generalized Chaplygin Gas (GCG) model. Rather surprisingly, we find that data allow models with $α> 1$. We have studied how the GCG adjusts flat and non-flat models, and our results show that GCG is consistent with flat case upto 68% confidence level. Actually this holds even if one relaxes the flat prior assumption. We have also analysed what one should expect from a future experiment such as SNAP. We find that there is a degeneracy between the GCG model and a XCDM model with a phantom-like dark energy component.

9 pages, 10 eps figures, mn2e style, detail study about degeneracy between GCG and phantom type XCDM has been included. This is the same version accepted for publication in Monthly Notices of the Royal Astronomical Society