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Title:
Bayesian Statistics and Parameter Constraints on the Generalized Chaplygin Gas Model Using SNe ia Data
Authors:
Colistete, R.; Fabris, J. C.; Gonçalves, S. V. B.
Affiliation:
AA(Universidade Federal do Espírito Santo, Departamento de Física, Av. Fernando Ferrari s/n - Campus de Goiabeiras, CEP 29060-900, Vitória, Espírito Santo, , Brazil; ), AB(Universidade Federal do Espírito Santo, Departamento de Física, Av. Fernando Ferrari s/n - Campus de Goiabeiras, CEP 29060-900, Vitória, Espírito Santo, , Brazil; ), AC(Universidade Federal do Espírito Santo, Departamento de Física, Av. Fernando Ferrari s/n - Campus de Goiabeiras, CEP 29060-900, Vitória, Espírito Santo, , Brazil; )
Publication:
International Journal of Modern Physics D, Volume 14, Issue 05, pp. 775-796 (2005). (IJMPD Homepage)
Publication Date:
00/2005
Origin:
WSPC
Keywords:
Dark energy, Chaplygin gas, type Ia supernova
DOI:
10.1142/S0218271805006729
Bibliographic Code:
2005IJMPD..14..775C

Abstract

The type Ia supernovae (SNe Ia) observational data are used to estimate the parameters of a cosmological model with cold dark matter and the generalized Chaplygin gas model (GCGM). The GCGM depends essentially on five parameters: the Hubble constant, the parameter bar A related to the velocity of the sound, the equation of state parameter α, the curvature of the Universe and the fraction density of the generalized Chaplygin gas (or the cold dark matter). The parameter α is allowed to take negative values and to be greater than one. The Bayesian parameter estimation yields α = - 0.86+6.01-0.15, H0 = 62.0+1.32-1.42 \ km/Mpc.s, Ω k0 = -0.74-1.32+1.42, Ω m0 = 0.00+0.86-0.00, Ω c0 = 1.39+1.21-1.25, bar A =1.00+0.00-0.39, t0 = 15.3+4.2-3.2 and q0 = -0.80+0.86-0.62, where t0 is the age of the Universe and q0 is the value of the deceleration parameter today. Our results indicate that a Universe completely dominated by the generalized Chaplygin gas is favored, which reinforces the idea that the this gas may unify the description for dark matter and dark energy, at least as far as the SNe Ia data is concerned. A closed and accelerating Universe is also favored. The traditional Chaplygin gas model (CGM), α = 1 is not ruled out, even if it does not give the best-fitting. Particular cases with four or three independent free parameters are also analyzed.
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