Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Sino-German 6cm polarization survey of the Galactic plane VII. Small
  supernova remnants   We study the spectral and polarization properties of supernova remnants
(SNRs) based on our 6cm survey data. The observations were taken from the
Sino-German 6cm polarization survey of the Galactic plane. By using the
integrated flux densities at 6cm together with measurements at other
wavelengths from the literature we derive the global spectra of 50 SNRs. In
addition, we use the observations at 6cm to present the polarization images of
24 SNRs. We derived integrated flux densities at 6cm for 51 small SNRs with
angular sizes less than 1 degree. Global radio spectral indices were obtained
in all the cases except for Cas A. For SNRs G15.1-1.6, G16.2-2.7, G16.4-0.5,
G17.4-2.3, G17.8-2.6, G20.4+0.1, G36.6+2.6, G43.9+1.6, G53.6-2.2, G55.7+3.4,
G59.8+1.2, G68.6-1.2, and G113.0+0.2, the spectra have been significantly
improved. From our analysis we argue that the object G16.8-1.1 is probably an
HII region instead of a SNR. Cas A shows a secular decrease in total intensity,
and we measured a flux density of 688+/-35 Jy at 6cm between 2004 and 2008.
Polarized emission from 25 SNRs were detected. For G16.2-2.7, G69.7+1.0,
G84.2-0.8 and G85.9-0.6, the polarized emission is detected for the first time
confirming them as SNRs. High frequency observations of SNRs are rare but
important to establish their spectra and trace them in polarization in
particular towards the inner Galaxy where Faraday effects are important.

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The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
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The categories of this paper are: chao-dyn
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The categories of this paper are: supr-con
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The categories of this paper are: adap-org
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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: q-bio
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The categories of this paper are: comp-gas
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The categories of this paper are: plasm-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: physics
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The categories of this paper are: stat