Análise de explosões solares em 45 e 90 ghz observadas por POEMAS com medidas de polarização
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Tipo
Tese
Data de publicação
2020-03-26
Periódico
Citações (Scopus)
Autores
Silva, Douglas Félix da
Orientador
Valio, Adriana Benetti Marques
Título da Revista
ISSN da Revista
Título de Volume
Membros da banca
Costa, Joaquim Eduardo Rezende
Silva, Jorge Fernando Valle
Simões, Paulo José de Aguiar
Szpigel, Sérgio
Silva, Jorge Fernando Valle
Simões, Paulo José de Aguiar
Szpigel, Sérgio
Programa
Ciências e Aplicações Geoespaciais
Resumo
Solar flares, resulting from the activity of the Sun, are among the most energetic
phenomena in the Solar System, and in the most extreme cases directly affect
our highly technological society. In this work, we analyze solar flares detected at
millimeter, centimeter, and X-ray wavelengths. Solar flares observed in these energy
bands allow the diagnostics of accelerated electrons and magnetic field values where
the radio emission is produced. To better understand the accelerated electrons and
magnetic fields involved in the flares, two methods were explored. We report on the
first use of polarization masurements of solar flares at millimetre wavelengths to
investigate the configuration of the magnetic field and determine the population of
accelerated electrons by studying the signatures of radio and hard X-ray spectra.
To model the magnetic configuration, two solar flares were analyzed. These were
observed by the POlarization Emission of the Millimeter Activity of the Sun system
(POEMAS) telescopes. Additional spectral data at microwaves from 1 to 15
GHz were obtained from the Radio Solar Telescope Network (RSTN) and at high
frequencies (212 and 405 GHz) by the Submillimetre Solar Telescope (SST). X-ray
data from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI)
were used to characterize the morphology of the source, also the 335 Å images and
magnetograms of active regions from the Solar Dynamic Observatory (SDO) were
used to infer the magnetic loop geometry. The flux density and polarization spectra
at radio wavelengths were fit using a model simulating the gyroemission in a 3D
structure of a non-homogeneous magnetic loop. The second approach analyses the
accelerated particles at different frequencies. For this, we investigated ten solar flares
that occurred between 2011 and 2013, observed in radio from 5 to 212 GHz (RSTN,
POEMAS, SST) and X-rays up to 300 keV and 1000 keV in one case (Rhessi and
Fermi). The spectral index was calculated by fitting the Ramaty gyrosynchrotron
emission model to the observed radio spectrum, while the hard X-ray spectra were
fitted using a model of thermal plus nonthermal emission of accelerated electrons
with a power-law distribution. Finally, the results of both indices were compared,
yielding a harder radio index than that obtained in X-rays. Except for one event
detected by Fermi up to 1 MeV that was studied in detail
Descrição
Palavras-chave
explosões solares , arco magnético , polarização , espectro rádio , raios X
Assuntos Scopus
Citação
SILVA, Douglas Félix da. Análise de explosões solares em 45 e 90 ghz observadas por POEMAS com medidas de polarização. 2020. 93 f. Tese (Ciências e Aplicações Geoespaciais) - Universidade Presbiteriana Mackenzie, São Paulo, 2020.