Solar Radio Burst and Solar Wind Associations with Inferred Near-Relativistic Electron Injections

The solar injections of near-relativistic (NR) electron events observed at 1 AU appear to be systematically delayed by ~10 minutes from the associated flare impulsive phases. We compare inferred injection times of 80 electron events observed by the 3DP electron detector on the Wind spacecraft with 40-800 MHz solar observations by the AIP radio telescope in Potsdam-Tremsdorf, Germany. Other than preceding type III bursts, we find no single radio signature characteristic of the inferred electron injection times. The injection delays from the preceding type III bursts do not correlate with the 1 AU solar wind β_p or B, but do correlate with densities n_e and inversely with speeds V_SW, consistent with propagation effects. About half of the events are associated with metric or decametric-hectometric (dh) type II bursts, but most injections occur before or after those bursts. Electron events with long (≥2 hr) beaming times at 1 AU are preferentially associated with type II bursts, which supports the possibility of a class of shock-accelerated NR electron events.