Magnetic-field Amplification by Turbulence in a Relativistic Shock Propagating Through an Inhomogeneous Medium

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 inhomogeneity, and the magnetic field is strongly amplified due to the str...

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Bibliographic Details
Published in:The Astrophysical journal 2011-01, Vol.726 (2), p.62-jQuery1323911895989='48'
Main Authors: Mizuno, Yosuke, Pohl, Martin, Niemiec, Jacek, Zhang, Bing, Nishikawa, Ken-Ichi, Hardee, Philip E
Format: Article
Language:English
Subjects:
AMPLIFICATION
Astronomy
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Earth, ocean, space
Exact sciences and technology
FLUID MECHANICS
HYDRODYNAMICS
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MECHANICS
SHOCK WAVES
SIMULATION
TURBULENCE
TWO-DIMENSIONAL CALCULATIONS
VELOCITY
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Summary: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 inhomogeneity, 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 two-dimensional simulations. The magnetic energy spectrum is flatter than the Kolmogorov spectrum and indicates that a so-called small-scale dynamo is occurring in the postshock region. We also find that the amount of magnetic-field amplification depends on the direction of the mean preshock magnetic field, and the timescale of magnetic-field growth depends on the shock strength.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/726/2/62