Spectral Trends of Solar Bursts at Sub-THz Frequencies

Autor: A. S. Kudaka, Pierre Kaufmann, C. G. Giménez de Castro, A. B. M. Valio, Jean-Pierre Raulin, Emilia Correia, P. Pereyra, L. O. T. Fernandes, A. Marun
Rok vydání: 2017
Předmět:
Zdroj: Solar Physics. 292
ISSN: 1573-093X
0038-0938
Popis: Previous sub-THz studies were derived from single-event observations. We here analyze for the first time spectral trends for a larger collection of sub-THz bursts. The collection consists of a set of 16 moderate to small impulsive solar radio bursts observed at 0.2 and 0.4 THz by the Solar Submillimeter-wave Telescope (SST) in 2012 – 2014 at El Leoncito, in the Argentinean Andes. The peak burst spectra included data from new solar patrol radio telescopes (45 and 90 GHz), and were completed with microwave data obtained by the Radio Solar Telescope Network, when available. We critically evaluate errors and uncertainties in sub-THz flux estimates caused by calibration techniques and the corrections for atmospheric transmission, and introduce a new method to obtain a uniform flux scale criterion for all events. The sub-THz bursts were searched during reported GOES soft X-ray events of class C or larger, for periods common to SST observations. Seven out of 16 events exhibit spectral maxima in the range 5 – 40 GHz with fluxes decaying at sub-THz frequencies (three of them associated to GOES class X, and four to class M). Nine out of 16 events exhibited the sub-THz spectral component. In five of these events, the sub-THz emission fluxes increased with a separate frequency from that of the microwave spectral component (two classified as X and three as M), and four events have only been detected at sub-THz frequencies (three classified as M and one as C). The results suggest that the THz component might be present throughout, with the minimum turnover frequency increasing as a function of the energy of the emitting electrons. The peculiar nature of many sub-THz burst events requires further investigations of bursts that are examined from SST observations alone to better understand these phenomena. Fil: Fernandes, L. O. T.. Universidade Presbiteriana Mackenzie; Brasil Fil: Kaufmann, Pierre. Universidade Estadual de Campinas; Brasil. Universidade Presbiteriana Mackenzie; Brasil Fil: Correia, E.. Instituto Nacional de Pesquisas Espaciais; . Universidade Presbiteriana Mackenzie; Brasil Fil: Giménez de Castro, C. G.. Universidade Presbiteriana Mackenzie; Brasil Fil: Kudaka, A. S.. Universidade Presbiteriana Mackenzie; Brasil Fil: Marun, Adolfo Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; Argentina Fil: Pereyra, Pablo Florencio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Complejo Astronómico ; Argentina Fil: Raulin, J. P.. Universidade Presbiteriana Mackenzie; Brasil Fil: Valio, A. B. M.. Universidade Presbiteriana Mackenzie; Brasil
Databáze: OpenAIRE
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