Inflação em sistemas com fluidos de radiação com viscosidade e dissipação e análise de estabilidade

• Autor(a) principal: Vicente, Gustavo dos Santos
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/12949
• topic: Cosmology; Field Theory; Inflationary Universe; Bulk Viscosity; Cosmologia; Teoria de Campos; Universo Inflacionário; Viscosidade Volumar; CNPQ::CIENCIAS EXATAS E DA TERRA::ASTRONOMIA::ASTROFISICA EXTRAGALACTICA::COSMOLOGIA

This work presents a study of the stability of the equations of warm inflation with a viscous radiation fluid. The viscosity of the fluid arises from the constant decay of particles into the fluid itself, due to the dissipation of the scalar field of inflation, the inflaton. This viscosity, which can be a bulk or a shear viscosity, is treated in terms of nonequilibrium thermodynamical theories. This study is limited to the warm inflation background equations, so that only bulk viscosity has a significant effect, being the shear viscosity important only in the context of cosmological perturbations. The description of viscosity in terms of a nonequilibrium thermodynamics, however, can not be univocally performed, because the unique information we have about irreversible processes is the second law of thermodynamics. Therefore, we set off in search of theories that are in accordance with this law and that, by plausible arguments, are capable to describe the behavior of the dissipative fluxes near equilibrium. The aim of this work is to study the stability of viscous warm inflation for causal and noncausal theories for the the viscous radiation fluid, so that the impact of viscosity and the relevance of considering causality can be observed. For the radiation fluid, the considered theories are the Eckart noncausal theory and causal ones from Israel-Stewart and from Denicol et al (nonlinear causal dissipative hydrodynamics). We obtain from causal theories, as it was expected, in addition to being, by definition, consistent regarding the finiteness of the propagations velocity of the dissipative fluxes, make the dynamical system stable for viscosity values further away from equilibrium. It's clearly observed, either, that the theory from Denicol et al in the most robust in that sense. This work, therefore, aims to continue the study of nonisentropic effects on inflation, since, in addition to the inflaton's dissipation in warm inflation, the impact of viscosity has attracted considerable interest.