Formação de estrutura em um universo viscoso

• Ano de defesa: 2018
• Autor(a) principal: Barbosa, Carolina Martins de Siqueira
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Doutorado em Física; Centro de Ciências Exatas; UFES; Programa de Pós-Graduação em Física
• Palavras-chave em Português: Cosmology; Dark Matter; Viscosity; Cosmologia; Matéria escura; Viscosidade; Matéria escura (Astronomia); Física; 53
• Link de acesso: http://repositorio.ufes.br/handle/10/7390

The cosmological standard model considers dark matter and dark energy, important components to explain observed phenomena in the Universe, contribute for about 95% of the total cosmic energy budget, while baryons and radiation with a small fraction of less than 5% of the total cosmic energy. Cold Dark Matter is considered to have equation of state of zero pressure, however its nature is one of the greatest mysteries of cosmology, and assume a dust-like equation of state can be a mistake. Viscosities are constantly present in nature, and is natural to think that dark matter must also have viscous properties. In this work we consider the study of a dark matter with viscous properties, which have a nonzero equation of state with negative pressure (since viscosities are dissipative mechanisms). Two viscosities are considered here: bulk and shear. The main goal of this work is study how the inclusion of shear viscosity impacts on the structure formation. A secondary goal is to investigate the relation of shear viscosity with models of modi ed gravity, using a phenomenological parametrization.