Electron and proton acceleration during the first ground level enhancement of solar cycle 24

Abstract

High-energy particles were recorded by near-Earth spacecraft and ground-based neutron monitors (NMs) on 2012 May 17. This event was the first ground level enhancement (GLE) of solar cycle 24. In this study, we try to identify the acceleration source(s) of solar energetic particles by combining in situ particle measurements from the WIND/3DP, GOES 13, and solar cosmic rays registered by several NMs, as well as remote-sensing solar observations from SDO/AIA, SOHO/LASCO, and RHESSI. We derive the interplanetary magnetic field (IMF) path length (1.25 +/- 0.05 AU) and solar particle release time (01:29 +/- 00:01 UT) of the first arriving electrons by using their velocity dispersion and taking into account contamination effects. We found that the electron impulsive injection phase, indicated by the dramatic change in the spectral index, is consistent with flare non-thermal emission and type III radio bursts. Based on the potential field source surface concept, modeling of the open-field lines rooted in the active region has been performed to provide escape channels for flare-accelerated electrons.Meanwhile, relativistic protons are found to be released 10 minutes later than the electrons, assuming their scatter-free travel along the same IMF path length. Combining multi-wavelength imaging data of the prominence eruption and coronal mass ejection (CME), we obtain evidence that GLE protons, with an estimated kinetic energy of 1.12 GeV, are probably accelerated by the CME-driven shock when it travels to 3.07 solar radii. The time-of-maximum spectrum of protons is typical for shock wave acceleration.

References in corpus (4)

• The acceleration characteristics of solar energetic particles in the 2000 July 14 event
• Solar source of energetic particles in interplanetary space during the 2006 December 13 event
• Coronal jets, magnetic topologies, and the production of interplanetary electron streams
• Major electron events and coronal magnetic configurations of the related solar active regions

Cited by in corpus (11)

• Formation and Eruption of an Active Region Sigmoid: I. Study by Nonlinear Force-Free Field Modeling
• Tracking the Evolution of A Coherent Magnetic Flux Rope Continuously from the Inner to the Outer Corona
• Homologous Flux Ropes Observed by SDO/AIA
• CME Magnetic Structure and IMF Preconditioning Affecting SEP Transport
• Statistical analysis of interplanetary magnetic field path lengths from solar energetic electron events observed by WIND
• Estimation of the release time of solar energetic particles near the Sun
• Multi-spacecraft observations and transport simulations of solar energetic particles for the May 17th 2012 event
• Waiting time distribution of solar energetic particle events modeled with a non-stationary Poisson process
• Three-stage Acceleration of Solar Energetic Particles Detected by Parker Solar Probe
• Coronal magnetic topology and the production of solar impulsive energetic electrons
• New classification parameter of solar flares based on the maximum flux in soft X-rays and on duration of flare