Particle Acceleration at the Pileup Collision of the Twin Shock

Xin Wang, Joe Giacalone, Yihua Yan, Mingde Ding, Chuan Li, Hong Lu, Hao Shan

Research output: Contribution to journalArticle

Abstract

Ground-level enhancement (GLE) events are often associated with large gradual solar events such as fast coronal mass ejections (CMEs), but not all fast CMEs lead to GLE events. Is there a type of coordinated CME that could produce GLEs with larger intensity and higher energies than those in the normal fast isolated CMEs? Here we propose a twin-shock scenario driven by the twin CME coordinately, in which the posterior shock catches up with the preceding shock and has a pileup collision. In the present study, we chose the first GLE event of the solar cycle 24 occurring on 2012 May 17 as an example to investigate the probable association with the twin-shock scenario. We use a dynamic Monte Carlo method to examine the energy spectrum with relevance to the GLE event. In the twin-shock scenario, the seed energetic particles produced by the normal preceding shock can be injected into the posterior shock for reacceleration efficiently. As a result, we obtain the detailed energy spectrum of the solar energetic particles (SEPs) with different behaviors at the related episodes of the twin-shock evolution. Therefore, we predict that the pileup collision of the twin shock would dominate a concave energy spectral slope in the 2012 May 17 SEP event.

Original languageEnglish (US)
Article number66
JournalAstrophysical Journal
Volume885
Issue number1
DOIs
StatePublished - Nov 1 2019

Keywords

  • Sun: coronal mass ejections (CMEs)
  • acceleration of particles
  • shock waves
  • solar wind

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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