Emissividade de neutrinos pelo processo Urca direto na presença de um campo magnético

• Autor(a) principal: Coelho, Eduardo Lenho
• Data de Publicação: 2015
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/12850
• topic: Equation of State; Neutron Stars; Magnetic field; Direct Urca process; Equação de Estado; Estrelas de Nêutrons; Campo magnético; Processo Urca direto; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA::FISICA NUCLEAR

Neutron stars are born with high temperatures (~ 1011 K) and during a few seconds suffer rapid cooling by emission of neutrinos. The direct Urca process is the main mechanism to explain this loss of energy. The question about the cooling of neutron stars is a question of great interest because his understanding may provide important informations about the interior constitution of the star. In the existing literature to date, the emissivity of neutrinos is calculated considering the nucleons as non-relativistic particles when are considered all the Landau levels of charged particles. On the other hand, the emissivity of neutrinos for relativistic nucleons is calculated considering only the first Landau level (for stong magnetic field). For weak magnetic fields, where more than one Landau level is occupied, the corresponding emissivity is used to zero field. In this Work we apply the Weinberg-Salan theory for weak interactions in calculating the emissivity of neutrinos with and without magnetic field present in a fully relativistic calculation for the nucleons and considering all Landau levels. This is the original contribution of the work. To describe the matter at high densities, we use relativistic mean field theory to zero temperature that includes only the baryon octet and the lightest leptons. We present the results for the neutrino emissivity, where it's evident the occupation of the different Landau levels as function of magnetic field.