Observations of Outward-propagating and Mirroring of the Same Energetic Electrons by Wind

Abstract

We report an energetic electron event observed by the Wind spacecraft in which electrons were first detected to propagate away from the Sun, and subsequently detected to propagate back toward the Sun. Using the recently developed fractional velocity dispersion analysis (FVDA), the path lengths corresponding to these two sequential electron signals were found to be ∼1.5 and ∼3.1 au. The inferred release times for both populations were found to be the same, within uncertainty. No bidirectional halo electrons were identified during the event, indicating that the electrons were not propagating within a closed magnetic field configuration (e.g., a magnetic flux rope). These observations suggest that the same energetic electrons were observed twice at 1 au, with the second time being due to reflection occurring beyond 1 au, by perhaps magnetic kinks caused by a coronal mass ejection-driven shock.