Simulation of Subterahertz Emission from the April 2, 2017 Solar Flare Based on the Multiwavelength Observations

Abstract

Millimeter (93 and 140 GHz) emission of the М6.4 solar flare detected on April 2, 2017 in the NOAA 12644 active region by the RT-7.5 telescope of the Bauman Moscow State Technical University is analyzed using the observational data provided by the Radio Solar Telescope Network (4.9, 8.8, and 15.4 GHz); the SDO/AIA satellites (Etreme Ultraviolet); and GOES, RHESSI, and Konus-Wind (X-rays). It is found that the spectral flux density of millimeter emission increases with frequency throughout the entire burst. The similarity between the profiles of millimeter and soft-X-ray radiation suggests that the burst is of a thermal nature. It follows from the results of calculations of the differential emission measure of coronal plasma based on the SDO/AIA data that its contribution to millimeter emission of the flare is negligible. The simulation of thermal emission of chromospheric flare plasma in the model of Machado (Machado et al., 1980) yields millimeter fluxes that are by several times lower than the observed ones. The physical implications of these results are discussed.