Authors: S. Roy (Center for Astrophysics | Harvard & Smithsonian), K. Reeves (Center for Astrophysics | Harvard & Smithsonian), C. Moore (Center for Astrophysics | Harvard & Smithsonian), D. Tripathi (Inter-University Centre for Astronomy and Astrophysics), S. Musset (European Space Research and Technology Centre)

The energy in solar flares is released impulsively and partially converted into the hot plasma’s thermal energy and the non-thermal particles’ kinetic energy. The statistical studies of a large sample of various energy classes suggest the existence of an additional energy source and an energy transport mechanism. Understanding the partition of these two energies is essential to understanding the energy release and transport mechanism and the particle acceleration in solar flares. Despite several efforts, we still have not reached any consensus regarding this partition. In addition, most studies have looked at the partition of the thermal and non-thermal energy averaged over the whole duration of the flares for flares of various classes.

We study an X-class (Oct 28th, 2021) and an M-class (Nov 29th, 2020) flare to understand the evolution of the partition of the thermal and non-thermal energies. We determine the thermal energy content and its evolution throughout the flares and how the contribution of thermal energy to the global energy budget changes during the flare. The bulk thermal energies of the flares are obtained from images from the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO), the Hinode X-ray Telescope and the Spectrometer/Telescope for Imaging X-rays(STIX). We calculate the Differential Emission Measure to infer the thermal energy as a function of time. We also use spectra obtained from the STIX onboard the Solar Orbiter for the X-class flare to better estimate the thermal component and hard X-ray data from the Fermi satellite for the M-class flare to understand the non-thermal energy evolution. We find the peak thermal energy ~ 6 x 10^{30} and 4 x 10^{30} ergs, respectively,  for the two flares we study. We also explore the effects of volume estimation of the flare arcade as a function of time on the thermal energy estimates. This demonstrates the necessity of high spatial resolution imaging at various wavelengths from multiple vantage points.