Speaker
Description
First name: Robert C.
Last name: Allen
All authors: Robert C. Allen, G. C. Ho, G. M. Mason, Z. Ding, M. H. Walker, A. Kouloumvakos, R. F. Wimmer-Schweingruber, J. Rodriguez-Pacheco, S. K. Vines, S. Hart, R. J. Filwett, Z. Xu, and C. M. S. Cohen
Abstract: Investigations of solar energetic particles (SEPs) have long utilized the dispersive nature of onset times, i.e., earlier arrival of higher-energy particles compared to lower-energy particles, to infer information such as the path length to the acceleration site at the time of initial particle release. However, recent observations by Solar Orbiter and Parker Solar Probe have begun to characterize SEP events with an apparent delay in arrival times of the higher-energy portion of the particle distribution, above a critical energy separating the delayed particles from that of the typical velocity dispersion signature at lower energies. Features of these delayed maximum energy (DME) SEP events may provide new insight into the impacts of magnetic connectivity to locations along an expanding coronal mass ejection (CME)-driven shock wave, variations of acceleration along the shock surface, and transport effects in the inner heliosphere. This presentation focuses on the occurrence rate and characteristics of DME events observed by Solar Orbiter and also highlights the findings of other recent observational and modeling studies on DME events. These studies indicate that DME events are due to inner heliospheric effects, and are not coronal in origin, consistent with previous observations and interpretations of SEP events connected westward of the associated flare.