The Production of Near-Relativistic Electrons by CME-Driven Shocks

Abstract

The solar sources of near-relativistic (E > 30 keV) electron events observed at I AU are poorly understood. In general, the solar injection times deduced from the observed I AU onset times and assumed 1.2 AU travel distances yield injection times about 10 minutes after the associated flare impulsive phases and type III radio burst times. One interpretation is that the apparent delays occur in the interplanetary medium, probably due to scattering of the electrons. If the injection times are delayed from the impulsive phases, the electron acceleration might take place in CME-driven shocks. Here a large number of electron events observed with the UC/Berkeley 3DP detector on the Wind spacecraft are compared with CMEs observed by the Lasco coronagraph on SOHO and with type 11 bursts observed by the 40 to 800 MHz radio receiver at the Astrophysikalisches Institut Potsdam (AIP) and by the 20 kHz to 14 MHz WAVES instrument on the Wind spacecraft. The acceleration of at least some of the electron events is not consistent with the shock hypothesis.