Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Origin of Radial Magnetic Fields in Young Supernova Remnants   We study the radio emission from young supernova remnants by means of 3D
numerical MHD simulations of the Rayleigh-Taylor instability in the shell of
the remnant. The computation is carried out in spherical polar coordinates ($r,
\theta, \phi$) by using a moving grid technique which allows us to finely
resolve the shell. Three-dimensional result shows more turbulent (complex)
structures in the mixing region than the two-dimensional result, and the
instability is found to deform the reverse shock front. Stokes parameters (I,Q,
and U) are computed to study the radio properties of the remnant. The total
intensity map shows two distinctive regions (inner and outer shells). The inner
shell appears to be complex and turbulent exhibiting loop structures and plumes
as a result of the Rayleigh-Taylor instability, while the outer shell is faint
and laminar due to the shocked uniform ambient magnetic fields. The inner shell
resembles the observed radio structure in the main shell of young SNRs, which
is evidence that the Rayleigh-Taylor instability is an ongoing process in young
SNRs. When only the peculiar components of the magnetic fields generated by the
instability are considered, the polarization B-vector in the inner radio shell
is preferentially radial with about $20 \sim 50\%$ of fractional polarization
which is higher than the observed value. The fractional polarization is lowest
in the turbulent inner shell and increases outward, which is attributed to the
geometric effect. The polarized intensity is found to be correlated with the
total intensity. We demonstrate that the polarized intensity from the turbulent
region can dominate over the polarized intensity from the shocked uniform
fields if the amplified field is sufficiently strong. Therefore, we conclude
that the Rayleigh-Taylor instability can explain the dominant radial magnetic

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The categories of this paper are: hep-ex
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The categories of this paper are: nlin
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The categories of this paper are: physics
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The categories of this paper are: q-bio
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The categories of this paper are: mtrl-th
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The categories of this paper are: atom-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: q-alg
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The categories of this paper are: plasm-ph
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The categories of this paper are: eess
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The categories of this paper are: cond-mat
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The categories of this paper are: econ
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The categories of this paper are: bayes-an
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-ph
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The categories of this paper are: patt-sol