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Title: Energetic Particles of keV–MeV Energies Observed near Reconnecting Current Sheets at 1 au

Abstract

We provide evidence for particle acceleration up to ∼5 MeV at reconnecting current sheets in the solar wind based on both case studies and a statistical analysis of the energetic ion and electron flux data from the five Advanced Composition Explorer Electron, Proton, and Alpha Monitor (EPAM) detectors. The case study of a typical reconnection exhaust event reveals (i) a small-scale peak of the energetic ion flux observed in the vicinity of the reconnection exhaust and (ii) a long-timescale atypical energetic particle event (AEPE) encompassing the reconnection exhaust. AEPEs associated with reconnecting strong current sheets last for many hours, even days, as confirmed by statistical studies. The case study shows that time-intensity profiles of the ion flux may vary significantly from one EPAM detector to another partially because of the local topology of magnetic fields, but mainly because of the impact of upstream magnetospheric events; therefore, the occurrence of particle acceleration can be hidden. The finding of significant particle energization within a time interval of ±30 hr around reconnection exhausts is supported by a superposed epoch analysis of 126 reconnection exhaust events. We suggest that energetic particles initially accelerated via prolonged magnetic reconnection are trapped and reaccelerated in small- ormore » medium-scale magnetic islands surrounding the reconnecting current sheet, as predicted by the transport theory of Zank et al. Other mechanisms of initial particle acceleration can contribute also.« less

Authors:
 [1];  [2]
  1. Heliophysical Laboratory, Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Sciences (IZMIRAN), Moscow (Russian Federation)
  2. Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35805 (United States)
Publication Date:
OSTI Identifier:
22663463
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 843; 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; ELECTRONS; HELIOSPHERE; KEV RANGE; MAGNETIC FIELDS; MAGNETIC ISLANDS; MAGNETIC RECONNECTION; MEV RANGE 01-10; PROTONS; SOLAR PARTICLES; SOLAR WIND; SUN; TAIL IONS; TRANSPORT THEORY; TRAPPING; TURBULENCE

Citation Formats

Khabarova, Olga V., and Zank, Gary P. Energetic Particles of keV–MeV Energies Observed near Reconnecting Current Sheets at 1 au. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA7686.
Khabarova, Olga V., & Zank, Gary P. Energetic Particles of keV–MeV Energies Observed near Reconnecting Current Sheets at 1 au. United States. doi:10.3847/1538-4357/AA7686.
Khabarova, Olga V., and Zank, Gary P. Sat . "Energetic Particles of keV–MeV Energies Observed near Reconnecting Current Sheets at 1 au". United States. doi:10.3847/1538-4357/AA7686.
@article{osti_22663463,
title = {Energetic Particles of keV–MeV Energies Observed near Reconnecting Current Sheets at 1 au},
author = {Khabarova, Olga V. and Zank, Gary P.},
abstractNote = {We provide evidence for particle acceleration up to ∼5 MeV at reconnecting current sheets in the solar wind based on both case studies and a statistical analysis of the energetic ion and electron flux data from the five Advanced Composition Explorer Electron, Proton, and Alpha Monitor (EPAM) detectors. The case study of a typical reconnection exhaust event reveals (i) a small-scale peak of the energetic ion flux observed in the vicinity of the reconnection exhaust and (ii) a long-timescale atypical energetic particle event (AEPE) encompassing the reconnection exhaust. AEPEs associated with reconnecting strong current sheets last for many hours, even days, as confirmed by statistical studies. The case study shows that time-intensity profiles of the ion flux may vary significantly from one EPAM detector to another partially because of the local topology of magnetic fields, but mainly because of the impact of upstream magnetospheric events; therefore, the occurrence of particle acceleration can be hidden. The finding of significant particle energization within a time interval of ±30 hr around reconnection exhausts is supported by a superposed epoch analysis of 126 reconnection exhaust events. We suggest that energetic particles initially accelerated via prolonged magnetic reconnection are trapped and reaccelerated in small- or medium-scale magnetic islands surrounding the reconnecting current sheet, as predicted by the transport theory of Zank et al. Other mechanisms of initial particle acceleration can contribute also.},
doi = {10.3847/1538-4357/AA7686},
journal = {Astrophysical Journal},
number = 1,
volume = 843,
place = {United States},
year = {Sat Jul 01 00:00:00 EDT 2017},
month = {Sat Jul 01 00:00:00 EDT 2017}
}