X-ray fine structure of a limb solar flare revealed by Insight-HXMT, RHESSI and Fermi

TL;DR

This study analyzes a limb solar flare using multi-instrument X-ray and EUV data, revealing details about plasma heating, non-thermal energy dissipation, and the relationship between thermal and non-thermal energies in the solar atmosphere.

Contribution

It provides a comprehensive joint analysis of X-ray and EUV observations of a limb flare, highlighting the plasma heating processes and energy exchange mechanisms.

Findings

Lower corona source identified in X-ray data.

Non-thermal broken power law with low break energy (~15 keV).

Post-peak plasma heating observed in DEM analysis.

Abstract

We conduct a detailed analysis of an M1.3 limb flare occurring on 2017 July 3, which have the X-ray observations recorded by multiple hard X-ray telescopes, including Hard X-ray Modulation Telescope (Insight-HXMT), Ramaty High Energy Solar Spectroscopic Imager (RHESSI), and The Fermi Gamma-ray Space Telescope (FERMI). Joint analysis has also used the EUV imaging data from the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamic Observatory. The hard X-ray spectral and imaging evolution suggest a lower corona source, and the non-thermal broken power law distribution has a rather low break energy $\sim$ 15 keV. The EUV imaging shows a rather stable plasma configuration before the hard X-ray peak phase, and accompanied by a filament eruption during the hard X-ray flare peak phase. Hard X-ray image reconstruction from RHESSI data only shows one foot point source. We also determined the DEM for the peak phase by SDO/AIA data. The integrated EM beyond 10 MK at foot point onset after the peak phase, while the $>$ 10 MK source around reconnection site began to fade. The evolution of EM and hard X-ray source supports lower corona plasma heating after non-thermal energy dissipation. The combination of hard X-ray spectra and images during the limb flare provides the understanding on the interchange of non-thermal and thermal energies, and relation between lower corona heating and the upper corona instability.