Energy spectra of 3He-rich solar energetic particles associated with coronal waves

TL;DR

This study analyzes 32 3He-rich solar energetic particle events, revealing that coronal waves are linked to power-law spectra, suggesting a new acceleration or transport mechanism in the solar corona.

Contribution

It provides the first statistical evidence connecting coronal EUV waves with power-law energy spectra in 3He-rich SEPs, indicating a potential second-stage acceleration process.

Findings

Coronal waves are associated with power-law spectra in 3He-rich SEPs.

Jets and brightenings tend to produce rounded spectra.

Coronal waves may facilitate a second-stage acceleration or transport mechanism.

Abstract

In addition to their anomalous abundances, 3He-rich solar energetic particles (SEPs) show puzzling energy spectral shapes varying from rounded forms to power laws where the later are characteristics of shock acceleration. Solar sources of these particles have been often associated with jets and narrow CMEs, which are the signatures of magnetic reconnection involving open field. Recent reports on new associations with large-scale EUV waves bring new insights on acceleration and transport of 3He-rich SEPs in the corona. We examined energy spectra for 32 3He-rich SEP events observed by ACE at L1 near solar minimum in 2007-2010 and compared the spectral shapes with solar flare signatures obtained from STEREO EUV images. We found the events with jets or brightenings tend to be associated with rounded spectra and the events with coronal waves with power laws. This suggests that coronal waves may be related to the unknown second stage mechanism commonly used to interpret spectral forms of 3He-rich SEPs.