Bayesian analysis of the (generalized) Chaplygin gas and cosmological constant models using the 157 gold SNe Ia data

R Colistete, J C Fabris
2005 Classical and quantum gravity  
The generalized Chaplygin gas model (GCGM) contains 5 free parameters, here, they are constrained through the type Ia supernovae data, i.e., the "gold sample" of 157 supernovae data. Negative and large positive values for α are taken into account. The analysis is made by employing the Bayesian statistics and the prediction for each parameter is obtained by marginalizing on the remained ones. This procedure leads to the following predictions: α = - 0.75^+4.04_-0.24, H_0=65.00^+1.77_-1.75, Ω_k0 =
more » ... - 0.77^+1.14_-5.94, Ω_m0 = 0.00^+1.95_-0.00, Ω_c0 = 1.36^+5.36_-0.85, A̅ = 1.000^+0.000_-0.534. Through the same analysis the specific case of the ordinary Chaplygin gas model (CGM), for which α = 1, is studied. In this case, there are now four free parameters and the predictions for them are: H_0 = 65.01^+1.81_-1.71, Ω_k0 = - 2.73^+1.53_-0.97, Ω_m0 = 0.00^+1.22_-0.00, Ω_c0 = 1.34^+0.94_-0.70, A̅ = 1.000^+0.000_-0.270. To complete the analysis the ΛCDM, with its three free parameters, is considered. For all these models, particular cases are considered where one or two parameters are fixed. The age of the Universe, the deceleration parameter and the moment the Universe begins to accelerate are also evaluated. The quartessence scenario, is favoured. A closed (and in some cases a flat) and accelerating Universe is also preferred. The CGM case α = 1 is far from been ruled out, and it is even preferred in some particular cases. In most of the cases the ΛCDM is disfavoured with respect to GCGM and CGM.
doi:10.1088/0264-9381/22/14/001 fatcat:daldyxbnzfcana2jwrnmiysspu