Quantifying the Matter Inhomogeneities with Supernovae and Gamma-Ray Bursts / Quantificando as inomogeneidades da matéria com Supernovas e Gamma-Ray Bursts
AUTOR(ES)
Vinicius Consolini Busti
DATA DE PUBLICAÇÃO
2009
RESUMO
In this dissertation we study how the effects of matter (baryonic and dark) inhomogeneities modify the distances thereby affecting the determination of cosmological parameters. The inhomogeneities are phenomenologically described by the clumpiness parameter alpha and quantified through the equation distance proposed by ZeldovichKantowskiDyer Roeder (ZKDR). Further, by using Supernovae and Gamma-Ray Bursts separately, a chi-squared analysis was performed to constrain the parameter space for two distinct cosmological models, namely: the flat LambdaCDM model and the cold dark matter creation model. For the flat LambdaCDM model we have constrained the parameters alpha and OmegaM by considering a Gaussian prior for the Hubble parameter. A detailed analysis was also performed involving two different calibrations associated to the Gamma-Ray Bursts data: a calibration for the flat LambdaCDM model as well as for the cardassian model. We have verified that the results are weakly dependent on the adopted calibration. A joint analysis involving Supernovae and Gamma-Ray Bursts allowed us to break the degenerescence between the clumpiness parameter alpha and the matter density parameter OmegaM. By considering the calibration for the flat LambdaCDM model, the best fits obtained were equal to alpha = 1.0 and OmegaM = 0.30 with the parameters restricted on the intervals 0.78 gamma-ray bursts gamma-ray bursts inomogeneidades inhomogeneities supernovas supernovae cosmologia cosmology distances in cosmology distâncias em cosmologia
ASSUNTO(S)
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