Solar Flash Sub-Millimeter Wave Range Spectrum Part Radiation Modeling

Abstract

Currently, solar flares are under observation on the RT-7.5 radio telescope of BMSTU. This telescope operates in a little-studied range of the spectrum, at wavelengths of 3.2 and 2.2 mm (93 and 140 GHz), thereby providing unique information about parameters of the chromosphere plasma and zone of the temperature minimum. Observations on various instruments provided relatively small amount of data on the radio emission flare at frequencies close to 93 GHz, and at frequency of 140 GHz such observations were not carried out. For these reasons, data collected from the RT-7.5 radio telescope are of high value (Shustikov et al., 2012). This work describes modeling and gives interpretation of the reason for raising flux density spectrum of sub-millimeter radio frequency emission using as an example the GOES flare of class M 5.3 occurred on 04.07.2012 in the active region 11515. This flare was observed on the RT-7.5 radio telescope of BMSTU and was described by Shustikov et al. (2012) and by Smirnova et al. (2013), where it has been suggested that the reason for raising radio frequency emission is a bremsstrahlung of the thermal electrons in the hot plasma of the solar chromosphere. Rough estimates of the plasma temperature at the flare source were obtained. This paper proposes model calculations of the flux density spectrum of the sub-millimeter radio emission based on the gyrosynchrotron Fleischman-Kuznetsov code (Fleishman & Kuznetsov, 2010). Section 1 briefly describes observational data, tools and processing methods used in the work. Section 2 shows results of modeling the flare radio emission. Section 3 discusses results and conclusions. Numerical modeling the sub-millimeter part of the spectrum of the radio flux density for the GOES flare of class M5.3 has been carried out. This flare occurred in the active region 11515 on 04.07.2012. Modeling was based on the observations on the BMSTU’s RT-7.5 radio telescope. The paper draws conclusion based on the model that the reason for raising flux density spectrum of sub-millimeter radio emission of flare is thermal bremsstrahlung plasma radiation with a temperature of 0.1 mK.