Can substorm particle acceleration be applied to solar flares?

Birn, J., Battaglia, M., Fletcher, L. , Hesse, M. and Neukirch, T. (2017) Can substorm particle acceleration be applied to solar flares? Astrophysical Journal, 848(2), 116. (doi:10.3847/1538-4357/aa8ad4)

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Using test particle studies in the electromagnetic fields of three-dimensional magnetohydrodynamic (MHD) simulations of magnetic reconnection, we study the energization of charged particles in the context of the standard two-ribbon flare picture in analogy to the standard magnetospheric substorm paradigm. In particular we investigate the effects of the collapsing field ("collapsing magnetic trap") below a reconnection site, which has been demonstrated to be the major acceleration mechanism causing energetic particle acceleration and injections observed in Earth's magnetotail associated with substorms and other impulsive events. We contrast an initially force-free, high shear, field (low beta) with low and moderate shear, finite-pressure (high beta) arcade structures, where beta represents the ratio between gas (plasma) and magnetic pressure. We demonstrate that the energization affects large numbers of particles but the acceleration is modest in the presence of a significant shear field. Without incorporating loss mechanisms, the effect on particles at different energies is similar, akin to adiabatic heating, and thus not a likely mechanism to generate a power law tail onto a (heated or not heated) Maxwellian velocity distribution.

Item Type:Articles
Keywords:MHD - sun, corona - sun, magnetic fields, solar flares, particle acceleration.
Glasgow Author(s) Enlighten ID:Fletcher, Professor Lyndsay and Battaglia, Dr Marina
Authors: Birn, J., Battaglia, M., Fletcher, L., Hesse, M., and Neukirch, T.
Subjects:Q Science > QB Astronomy
Q Science > QC Physics
College/School:College of Science and Engineering > School of Physics and Astronomy
Research Group:Astronomy and Astrophysics
Journal Name:Astrophysical Journal
Journal Abbr.:ApJ
ISSN (Online):1538-4357
Copyright Holders:Copyright © 2017 American Astronomical Society
First Published:First published in Astrophysical Journal 848(2):116
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
631581Consolidated grant in solar and astrophysical plasmasLyndsay FletcherScience & Technology Facilities Council (STFC)ST/L000741/1S&E P&A - PHYSICS & ASTRONOMY