As supernovas tipo Ia e a cosmologia

• Autor(a) principal: Oliveira, Paulo Louzada Castro de
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/7419
• topic: Cosmology; Bayesian statistics; Dark matter; Dark Energy; Cosmologia; Supernova; Estatística Bayesiana; Matéria escura; Energia escura; Física; 53

This dissertation is dedicated to the investigation on the nature of the dark matter and dark energy in the Universe through the technique that uses the observations of explosions os supernovae type Ia as indicators of distances, used at the end of the last century to detect the acelerated expansion of the Universe. Since then some projects dedicated to observation of supernovae where executed and published their results, which are used here to estimate parameters and compare cosmological models. The objective of this work is to study the power of the test based on the distances to supernovae and its response to different cosmological models and free parameters. To begin with we review the standard model of Cosmology and the evidences that suport the existance of dark matter and dark energy, followed by a study on the supernovae itself and its various observational and astrophysical aspects that allow the construction of the magnitude calibration techniques and the estimatives of its distances. Before moving on to the cosmological analyses we introduce the appropriate tool which is the bayesian statistics, studied here only in its basic tools and aplications. At last we aply these tools to the supernovae data sets available in the literature know as the Gold, SNLS, Essence and Constitution, to study some cosmological models, beginning with the concordance ?CDM model and the ?CDM parametrization that tests the supposition that ?X = -1 for the dark energy. After that we test two dynamical vaccum energy ?(t) models and a special case of the quartessence Generalized Chaplygin Gas model. The results show that when used alone the supernovae data sets leeds to quite less expressive results when compared to the literature where they are used together with other evidences. And also two of the data sets including the most up to date show unexpected irregularities that point to the existance of still uncontrolled effects on the magnitude calibration techniques. Both results show that the cosmological test based on supernovae data will go through another significant improvement on its quality in the near future.