Contribuição de pósitrons e elétrons secundários para o espectro em rádio de explosões solares
Arquivos
Tipo
Dissertação
Data de publicação
2017-01-27
Periódico
Citações (Scopus)
Autores
Serra, Jordi Tuneu
Orientador
Szpigel, Sérgio
Título da Revista
ISSN da Revista
Título de Volume
Membros da banca
Raulin, Jean Pierre
Simões, Paulo José de Aguiar
Simões, Paulo José de Aguiar
Programa
Ciências e Aplicações Geoespaciais
Resumo
Recent observations of solar flares at high-frequencies in radio and in the
medium infrared have provided evidence of a new spectral component with fluxes
increasing with frequency in the sub-𝑇𝐻𝑧 to 𝑇𝐻𝑧 range. This new component occurs
simultaneously but is separated from the well-known microwave spectral component
that has a maximum at frequencies of order of tens of 𝐺𝐻𝑧, resulting in a doublespectrum
structure. Several mechanisms based on different emission processes have
been proposed to interpret the new 𝑇𝐻𝑧 spectral component but its origin still
remains unknown. The aim of this work is to study the mechanisms of production of
secondary electrons and positrons in high-energy nuclear processes (∼ 𝐺𝑒𝑉 ) which
occur in solar flares and its possible contribution to the 𝑇𝐻𝑧 spectral component via
the emission of gyrosynchrotron/synchrotron radiation. We also discuss the possible
contribution of low-energy secondary electrons (∼ 0.1 − 10 𝑀𝑒𝑉 ) to the microwave
spectrum of intense events. Using the package FLUKA, a Monte Carlo simulator for
calculations of particle transport and interactions in matter, we obtain the energy
distributions for secondary electrons and positrons generated by collisions between
accelerated protons or 𝛼-particles and nuclei from the ambient solar atmosphere. We
consider a simple model for the ambient solar atmosphere and beams of accelerated
protons or 𝛼-particles with power-law energy distribution and different angular
distributions. The emission spectrum of gyrosynchrotron/synchrotron radiation is
obtained by summing the contributions to the total flux density from the secondary
electrons and positrons, calculated using a code based on Ramaty’s algorithm from
the respective distributions of energy obtained with FLUKA.
Descrição
Palavras-chave
explosões solares , processos nucleares de alta energia , pósitrons e elétrons secundários , radiação giromagnética
Assuntos Scopus
Citação
SERRA, Jordi Tuneu. Contribuição de pósitrons e elétrons secundários para o espectro em rádio de explosões solares. 2017. 170 f. Dissertação( Ciências e Aplicações Geoespaciais) - Universidade Presbiteriana Mackenzie, São Paulo.