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Title: ASSOCIATION OF SUPRATHERMAL PARTICLES WITH COHERENT STRUCTURES AND SHOCKS

Various mechanisms have been proposed to explain observed suprathermal particle populations in the solar wind, including direct acceleration at flares, stochastic acceleration, shock acceleration, and acceleration by random compression or reconnection sites. Using magnetic field and suprathermal particle data from the Advanced Composition Explorer (ACE), we identify coherent structures and interplanetary shocks, and analyze the temporal association of energetic particle fluxes with these coherent structures. Coherent structures having a range of intensities are identified using the magnetic Partial Variance of Increments statistic, essentially a normalized vector increment. A stronger association of energetic particle flux in the 0.047-4.75 MeV range is found with intense magnetic discontinuities than is found with shocks. Nevertheless, the average profile of suprathermals near shocks is quite consistent with standard models of diffusive shock acceleration, while a significant amount of the energetic particles measured and strong discontinuities are found by ACE within six hours of a shock. This evidence supports the view that multiple mechanisms contribute to the acceleration and transport of interplanetary suprathermal particles.
Authors:
; ;  [1] ;  [2] ;  [3] ;  [4]
  1. Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)
  2. Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry CV4 7AL (United Kingdom)
  3. Department of Physics, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand)
  4. Department of Planetary Sciences and Lunar and Planetary Laboratory, University of Arizona, 1629 East University Boulevard, Tucson, AZ 85721 (United States)
Publication Date:
OSTI Identifier:
22215408
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 776; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; COMPRESSION; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; MEV RANGE; PLASMA; SHOCK WAVES; SOLAR WIND; STANDARD MODEL; STOCHASTIC PROCESSES