Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic fields in barred galaxies III: The southern peculiar galaxy NGC
  2442   Observations of the southern peculiar galaxy NGC 2442 with the Australia
Telescope Compact Array in total and linearly polarized radio continuum at 6cm
are presented and compared with previously obtained H$\alpha$ data. The
distribution of polarized emission, a signature of regular magnetic fields,
reveals some physical phenomena which are unusual among spiral galaxies. We
find evidence for tidal interaction and/or ram pressure from the intergalactic
medium compressing the magnetic field at the northern and western edges of the
galaxy. The radial component of the regular magnetic field in the northern arm
is directed away from the centre of the galaxy, a finding which is in contrast
to the majority of galaxies studied to date. The oval distortion caused by the
interaction generates a sudden jump of the magnetic field pattern upstream of
the inner northern spiral arm, similar to galaxies with long bars. An unusual
``island'' of strong regular magnetic field east of the galaxy is probably the
brightest part of a magnetic arm frequently seen in spiral galaxies, which
appear to be phase-shifted images of the preceding optical arm. The strong
magnetic field of the ``island'' indicates a past phase of active star
formation when the preceding optical arm was exposed to ram pressure.

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The categories of this paper are: atom-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-bio
4
The categories of this paper are: cond-mat
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The categories of this paper are: dg-ga
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The categories of this paper are: funct-an
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The categories of this paper are: adap-org
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The categories of this paper are: solv-int
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The categories of this paper are: nlin
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The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-th
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The categories of this paper are: cmp-lg