BETOCS using the 157 gold SNe Ia Data : Hubble is not humble

Abstract

The type Ia supernovae observational data is one of the most important in observational cosmology nowadays. Here we present the first public version of BETOCS (BayEsian Tools for Observational Cosmology using SNe Ia), which is a powerful and high productivity tool aimed to help the theoretical physicist community investigate cosmological models using type Ia supernovae (SNe Ia) observational data. BETOCS is applied to the generalized Chaplygin gas model (GCGM), traditional Chaplygin gas model (CGM) and $Λ$CDM, ranging from 5 to 3 free parameters, respectively. The ``gold sample'' of 157 supernovae data is used. It is shown that the Chaplygin gas scenario is viable (in most cases the $Λ$CDM is disfavoured) and the quartessence scenario (that unifies the description for dark matter and dark energy) is favoured. The Hubble parameter ($H_0$) is important and should not be fixed and it can be estimated or marginalized with or without the Hubble Space Telescope prior.