Solar Energetic Electron Events Associated with Hard X-ray Flares
Abstract
We presented a comparison survey of 16 solar energetic electron (SEE) events measured by WIND/3DP with associated hard X-ray (HXR) flares measured by RHESSI with good count statistics, from 2002 February to 2016 December. Among the 16 good cases, all show a double-power-law shape with a downward break at ~ 68keV in the electron peak flux versus energy spectrum at ~ 5-200keV; All cases show a clear single-power-law in the HXR peak flux versus energy spectrum, and a single-power-law in the flux versus energy spectrum of HXR-producing electrons derived via bremsstrahlung mechanisms. For SEEs, their acceleration site at the Sun should occur high (at a heliocentric altitude of ≧1.3 Rs (the average solar radius)), to remain a power-law spectrum extending down to ~ 5 keV during their anti-sunward escape into the interplanetary medium (IPM). For 14 out of 16 cases, the spectral index above the energy break of SEEs observed at 1AU basically agreed with the derived spectral index of HXR-producing electrons. However, the SEE spectral index below the energy break is all smaller than the HXR-producing electron spectral index. These results suggest that SEEs and HXR-producing electrons share a common origin and an additional acceleration could exist between the SEE source and the flare region. In addition, for cases with 3He/4He>0.01, the observed 3He/4He shows a correlation with the spectral index above the energy break of SEEs, indicating a possible relation of the 3He-rich ion acceleration at high corona with SEEs.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMSH045..05W
- Keywords:
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- 7519 Flares;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7845 Particle acceleration;
- SPACE PLASMA PHYSICS;
- 7846 Plasma energization;
- SPACE PLASMA PHYSICS;
- 7984 Space radiation environment;
- SPACE WEATHER