Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Diffuse Radio Sources in Groups and Poor Clusters   We have discovered new diffuse radio sources likely associated with groups of
galaxies at low redshift (0.01-0.04) and without apparent AGN by using the
WENSS and WISH catalogs to perform an unbiased survey. These sources resemble
the radio halos, mini-halos, and 'relics' of rich clusters, which are thought
to be powered by shocks and turbulence from infall into their deep potential
wells. Our detection of similar sources within the shallow potential wells of
groups of galaxies challenges this model. Their radio luminosities are
approximately two orders of magnitude higher than expected from the
extrapolation of the apparent rich cluster radio/X-ray luminosity relation.
Even if these sources are misidentified distant clusters, they would lie above
the apparent rich cluster radio/X-ray luminosity relation in the literature,
suggesting that detections of radio halos and relics thus far may be more
biased than previously thought.

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The categories of this paper are: eess
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The categories of this paper are: funct-an
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: gr-qc
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-th
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The categories of this paper are: econ
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The categories of this paper are: quant-ph
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The categories of this paper are: comp-gas
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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: nucl-th
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The categories of this paper are: q-fin
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The categories of this paper are: cs
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The categories of this paper are: math