Size distributions of solar flares and solar energetic particle events
Abstract
We suggest that the flatter size distribution of solar energetic proton (SEP) events relative to that of flare soft X-ray (SXR) events is primarily due to the fact that SEP flares are an energetic subset of all flares. Flares associated with gradual SEP events are characteristically accompanied by fast (>=1000 km s-1) coronal mass ejections (CMEs) that drive coronal/interplanetary shock waves. For the 1996-2005 interval, the slopes (α values) of power-law size distributions of the peak 1-8 Å fluxes of SXR flares associated with (a) >10 MeV SEP events (with peak fluxes >=1 pr cm-2 s-1 sr-1) and (b) fast CMEs were ~1.3-1.4 compared to ~1.2 for the peak proton fluxes of >10 MeV SEP events and ~2 for the peak 1-8 Å fluxes of all SXR flares. The difference of ~0.15 between the slopes of the distributions of SEP events and SEP SXR flares is consistent with the observed variation of SEP event peak flux with SXR peak flux.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 2012
- DOI:
- 10.1088/2041-8205/756/2/L29
- Bibcode:
- 2012ApJ...756L..29C
- Keywords:
-
- Sun: flares;
- Sun: particle emission;
- Sun: coronal mass ejections (CMEs);
- Sun: X-rays;
- gamma-rays