Near-relativistic electron emission following the 28 October 2003 X17 flare

Abstract

The 28 October 2003 solar flare event was one of the largest electron events above 50 keV of the current solar cycle. The event was associated with a major flare, at least one fast coronal mass ejection (CME), and a prominence eruption. The evolution of the electron spectrum for this event enables us to resolve three, or possibly four, separate electron sources. The source associated with the passage of a fast CME through the corona lasts about half an hour, has a very soft spectrum, and appears at 1 AU as a highly anisotropic beam. The most intense source has a weak outward anisotropy, lasts 2 days before starting a slow decay, and has a hard spectrum. The event is at its most intense around the arrival of the shock which is ahead of the CME, and this is also when the electron spectrum is hardest. One possible interpretation to explain the spectral and angular distribution properties of the electrons from this event is discussed.