Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Low Frequency Survey of the Galactic Plane Near l=11 degrees:
  Discovery of Three New Supernova Remnants   We have imaged a 1 deg^2 field centered on the known Galactic supernova
remnant (SNR) G11.2-0.3 at 74, 330, and 1465 MHz with the Very Large Array
radio telescope (VLA) and 235 MHz with the Giant Metrewave Radio Telescope
(GMRT). The 235, 330, and 1465 MHz data have a resolution of 25 arcsec, while
the 74 MHz data have a resolution of 100 arcsec. The addition of this low
frequency data has allowed us to confirm the previously reported low frequency
turnover in the radio continuum spectra of the two known SNRs in the field:
G11.2-0.3 and G11.4-0.1 with unprecedented precision. Such low frequency
turnovers are believed to arise from free-free absorption in ionized thermal
gas along the lines of site to the SNRs. Our data suggest that the 74 MHz
optical depths of the absorbing gas is 0.56 and 1.1 for G11.2-0.3 and
G11.4-0.1, respectively. In addition to adding much needed low frequency
integrated flux measurements for two known SNRs, we have also detected three
new SNRs: G11.15-0.71, G11.03-0.05, and G11.18+0.11. These new SNRs have
integrated spectral indices between -0.44 and -0.80. Because of confusion with
thermal sources, the high resolution (compared to previous Galactic radio
frequency surveys) and surface brightness sensitivity of our observations have
been essential to the identification of these new SNRs. With this study we have
more than doubled the number of SNRs within just a 1 deg^2 field of view in the
inner Galactic plane. This result suggests that future low frequency
observations of the Galactic plane of similar quality may go a long way toward
alleviating the long recognized incompleteness of Galactic SNR catalogs.

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The categories of this paper are: quant-ph
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The categories of this paper are: math
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The categories of this paper are: nucl-th
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The categories of this paper are: acc-phys
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The categories of this paper are: funct-an
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The categories of this paper are: q-bio
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The categories of this paper are: cond-mat
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The categories of this paper are: q-fin
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The categories of this paper are: supr-con
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The categories of this paper are: bayes-an
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The categories of this paper are: math-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-alg