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The Acceleration of Charged Particles at a Spherical Shock Moving through an Irregular Magnetic Field
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Giacalone_2017_ApJ_848_123.pdf
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FInal Published Version
Author
Giacalone, J.Affiliation
Univ Arizona, Dept Planetary SciIssue Date
2017-10-23Keywords
acceleration of particlesISM: magnetic fields
ISM: supernova remnants
shock waves
Sun: heliosphere
turbulence
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IOP PUBLISHING LTDCitation
The Acceleration of Charged Particles at a Spherical Shock Moving through an Irregular Magnetic Field 2017, 848 (2):123 The Astrophysical JournalJournal
The Astrophysical JournalRights
© 2017. The American Astronomical Society. All rights reserved.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
We investigate the physics of charged-particle acceleration at spherical shocks moving into a uniform plasma containing a turbulent magnetic field with a uniform mean. This has applications to particle acceleration at astrophysical shocks, most notably, to supernovae blast waves. We numerically integrate the equations of motion of a large number of test protons moving under the influence of electric and magnetic fields determined from a kinematically defined plasma flow associated with a radially propagating blast wave. Distribution functions are determined from the positions and velocities of the protons. The unshocked plasma contains a magnetic field with a uniform mean and an irregular component having a Kolmogorov-like power spectrum. The field inside the blast wave is determined from Maxwell's equations. The angle between the average magnetic field and unit normal to the shock varies with position along its surface. It is quasi-perpendicular to the unit normal near the sphere's equator, and quasi-parallel to it near the poles. We find that the highest intensities of particles, accelerated by the shock, are at the poles of the blast wave. The particles "collect" at the poles as they approximately adhere to magnetic field lines that move poleward from their initial encounter with the shock at the equator, as the shock expands. The field lines at the poles have been connected to the shock the longest. We also find that the highest-energy protons are initially accelerated near the equator or near the quasi-perpendicular portion of the shock, where the acceleration is more rapid.ISSN
1538-4357Version
Final published versionSponsors
NASA [NNX15AJ71G, NNX15AJ72G]; NSF [AGS1135432]Additional Links
http://stacks.iop.org/0004-637X/848/i=2/a=123?key=crossref.0603142fbd4539464a195c23fc28c723ae974a485f413a2113503eed53cd6c53
10.3847/1538-4357/aa8df1