Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Radio Spectral Index Variations and Physical conditions in Kepler's
  Supernova Remnant   A new epoch of VLA measurements of Kepler's supernova remnant was obtained to
make accurate measurements of the radio spectral index variations and
polarization. We have compared these new radio images with Halpha, infrared,
and X-ray data to better understand the three dimensional structure and
dynamics of Kepler, and to better understand the physical relationships between
the various nonthermal and thermal plasmas. Spatial variations in the radio
spectral index from -0.85 to -0.6 are observed between 6 cm and 20 cm. There is
a strong correspondence between the radial and azimuthal profiles of the radio,
X-ray, Halpha, and infrared emission in different locations around the remnant
although there is no single, global pattern. Spectral tomography shows that the
flat- and steep-spectrum radio emissions have distinct structures. The
flat-spectrum radio emission is found either at a larger radius than or
coincident with the steep-spectrum emission. We interpret these spectral
components as tracing forward- and reverse-shocked material, respectively. The
Halpha and IR images are very similar. Their leading edges are coincident and
are either in front of or coincident with the leading edges of the X-ray and
radio emission. The X-ray emission matches the Halpha and IR emission in
places, and in other places traces the steep-spectrum radio emission. In the
north there is also an anticorrelation in the azimuthal profiles around the
remnant of the flat-spectrum radio emission and the thermal X-ray, Halpha, and
IR emissions. We suggest that this could be due to a relative weakening of the
particle acceleration at the forward shock due to Alfven wave damping in
regions of high density.

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The categories of this paper are: adap-org
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The categories of this paper are: hep-th
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The categories of this paper are: ao-sci
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The categories of this paper are: cond-mat
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The categories of this paper are: solv-int
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The categories of this paper are: chem-ph
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The categories of this paper are: math
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The categories of this paper are: bayes-an
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The categories of this paper are: gr-qc
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The categories of this paper are: funct-an
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The categories of this paper are: hep-ex
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The categories of this paper are: eess
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The categories of this paper are: patt-sol
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The categories of this paper are: acc-phys
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-lat