Bi-directional streaming of particles accelerated at the STEREO-A shock on 2008 March 9

F. Fraschetti, J. Giacalone

Research output: Contribution to journalArticlepeer-review

Abstract

We present an interpretation of anisotropy and intensity of supra-thermal ions near a fast quasi-perpendicular reverse shock measured by Solar Terrestrial Relations Observatory Ahead (ST-A) on 2008 March 9. The measured intensity profiles of the supra-thermal particles exhibit an enhancement, or 'spike', at the time of the shock arrival and pitch-angle anisotropies before the shock arrival are bi-modal, jointly suggesting trapping of near-scatter-free ions along magnetic field lines that intersect the shock at two locations. We run test-particle simulations with pre-existing upstream magnetostatic fluctuations advected across the shock. The measured bi-modal upstream anisotropy, the nearly field-aligned anisotropies up to ∼15 min upstream of the shock, as well as the 'pancake-like' anisotropies up to ∼10 min downstream of the shock are well reproduced by the simulations. These results, in agreement with earlier works, suggest a dominant role of the large-scale structure (100s of supra-thermal proton gyroradii) of the magnetic field in forging the early-on particle acceleration at shocks.

Original languageEnglish (US)
Pages (from-to)2087-2093
Number of pages7
JournalMonthly Notices of the Royal Astronomical Society
Volume499
Issue number2
DOIs
StatePublished - Dec 1 2020

Keywords

  • acceleration of particles
  • shock waves
  • turbulence

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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