Gamma-ray emission and neutrons from solar flares recorded by the SONG instrument in 2001–2004

Abstract

The SONG instrument onboard the CORONAS-F satellite recorded gamma-ray emission with energy above 500 keV in 28 solar flares over three years of its in-orbit operation. According to the GOES classification, the X-ray importance of these flares lay within the range M1.4-X28. The gamma-ray energy recorded by SONG exceeded 4 MeV in 16 flares. Gamma-ray emission with energy up to 100 MeV was recorded in three events, more specifically, on August 25, 2001, October 28, 2003, and November 4, 2003. Increases in the count rate in the SONG channels that recorded neutrons with energies above 20 MeV were found during these three events. The energies of the recorded neutrons were estimated for the neutron increases. The time dependence of the neutron increases was compared with data from high-altitude ground-based neutron monitors that could, in principle, record the arrival of high-energy neutrons from the Sun. It should be noted that we detected series of flares with gamma-ray emission generated by the same active region (AR). The series in the last decade of August 2002 (AR NOAA 0069), the end of May 2003 (AR NOAA 0365), and the famous period of extreme solar activity in October–November 2003 associated with AR NOAA 0486 and AR NOAA 0501 are quite revealing. The catalog can be of use for future statistical and correlation analyses of solar flares.