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dc.contributor.authorGiacalone, J.
dc.date.accessioned2017-11-15T16:41:28Z
dc.date.available2017-11-15T16:41:28Z
dc.date.issued2017-10-23
dc.identifier.citationThe Acceleration of Charged Particles at a Spherical Shock Moving through an Irregular Magnetic Field 2017, 848 (2):123 The Astrophysical Journalen
dc.identifier.issn1538-4357
dc.identifier.doi10.3847/1538-4357/aa8df1
dc.identifier.urihttp://hdl.handle.net/10150/626061
dc.description.abstractWe 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.
dc.description.sponsorshipNASA [NNX15AJ71G, NNX15AJ72G]; NSF [AGS1135432]en
dc.language.isoenen
dc.publisherIOP PUBLISHING LTDen
dc.relation.urlhttp://stacks.iop.org/0004-637X/848/i=2/a=123?key=crossref.0603142fbd4539464a195c23fc28c723en
dc.rights© 2017. The American Astronomical Society. All rights reserved.en
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.subjectacceleration of particlesen
dc.subjectISM: magnetic fieldsen
dc.subjectISM: supernova remnantsen
dc.subjectshock wavesen
dc.subjectSun: heliosphereen
dc.subjectturbulenceen
dc.titleThe Acceleration of Charged Particles at a Spherical Shock Moving through an Irregular Magnetic Fielden
dc.typeArticleen
dc.contributor.departmentUniv Arizona, Dept Planetary Scien
dc.identifier.journalThe Astrophysical Journalen
dc.description.collectioninformationThis 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.en
dc.eprint.versionFinal published versionen
refterms.dateFOA2018-05-28T01:03:30Z
html.description.abstractWe 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.


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