TY - JOUR
T1 - Bi-directional streaming of particles accelerated at the STEREO-A shock on 2008 March 9
AU - Fraschetti, F.
AU - Giacalone, J.
N1 - Funding Information:
Helpful comments from the anonymous referee are acknowledged. The work of FF was supported, in part, by National Aeronautics and Space Administration (NASA) under Grants NNX15AJ71G and 80NSSC18K1213 and by National Science Foundation (NSF) under grant 1850774. JG acknowledges support fromNASA's Parker Solar Probe Mission (contract NNN06AA01C), 80NSSC18K1213 and NSF grant 1735422. FF thanks Drs Wimmer-Schweingruber and Heber for clarifications on PLASTIC and SEPT instruments, Dr. Yang for sharing PLASTIC data and Dr. L. Jian for comments on the manuscript. Computational resources supporting this work were provided by the Hipas supercomputer cluster at the University of Arizona. The STEREO/SEPT project is supported under Grant 50 OC 1702 by the German Bundesministerium f?r Wirtschaft through the Deutsches Zentrum f?r Luft- und Raumfahrt (DLR); the STEREO/PLASTIC by NASA grant 80NSSC20K0431. This paper uses data from the Heliospheric Shock Database, generated and maintained at the University of Helsinki. We acknowledge data providers(s), J. Luhmann at UCB/SSL and CDAWeb for providing visualisation tool for the high-resolution MAG time series.
Publisher Copyright:
© 2020 The Author(s).
PY - 2020/12/1
Y1 - 2020/12/1
N2 - 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.
AB - 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.
KW - acceleration of particles
KW - shock waves
KW - turbulence
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U2 - 10.1093/mnras/staa3021
DO - 10.1093/mnras/staa3021
M3 - Article
AN - SCOPUS:85096843248
VL - 499
SP - 2087
EP - 2093
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 2
ER -