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Magnetic field amplification by relativistic shocks in a turbulent medium

Published online by Cambridge University Press:  08 June 2011

Yosuke Mizuno
Affiliation:
CSPAR, The University of Alabama in Huntsville, 320 Sparkman Drive, NSSTC, Huntsville, AL 35805, USA email: mizuno@cspar.uah.edu
Martin Pohl
Affiliation:
Institute of Physics and Astronomy, Universität Potsdam, 14476 Potsdam-Golm, Germany
Jacek Niemiec
Affiliation:
Institute of Nuclear Physics PAN, Kraków, Poland
Bing Zhang
Affiliation:
Dept. of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154, USA
Ken-Ichi Nishikawa
Affiliation:
CSPAR, The University of Alabama in Huntsville, 320 Sparkman Drive, NSSTC, Huntsville, AL 35805, USA email: mizuno@cspar.uah.edu
Philip E. Hardee
Affiliation:
Dept. Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487, USA
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Abstract

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We perform two-dimensional relativistic magnetohydrodynamic simulations of a mildly relativistic shock propagating through an inhomogeneous medium. We show that the postshock region becomes turbulent owing to preshock density inhomogeneities, and the magnetic field is strongly amplified due to the stretching and folding of field lines in the turbulent velocity field. The amplified magnetic field evolves into a filamentary structure in our two-dimensional simulations. The magnetic energy spectrum is flatter than Kolmogorov and indicates that a so-called small-scale dynamo is operating in the postshock region. We also find that the amount of magnetic-field amplification depends on the direction of the mean preshock magnetic field.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2011

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