The Observed Spectrum of Solar Burst Continuum Emission in the Submillimeter Spectral Range

Abstract

Observations of solar flares at high frequencies suggest that a considerable fraction of the events present flat or even increasing flux spectra at frequencies above 35 GHz. This imposes restrictions on the gyrosynchrotron emission mechanism and source parameters. We analysed a sample of 115 microwave events in order to investigate their spectra at peak flux. The analysis shows that about 50% of the sample exhibits a flat and 25% an increasing spectrum between 19 and 35 GHz. This class of events is significant and must be considered in the models. In order to better define the characteristics of this class of events it is necessary to carry out observations at frequencies well above 50 GHz with high time resolution and high sensitivity.