Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The X-ray properties of the low-redshift quasar MRC 2251-178 and its
  environment: some surprises   MR 2251-178 was the first quasar initially discovered in X-rays, and the
first one found to host a warm absorber. Despite its many outstanding
multi-wavelength properties, MR 2251-178 has not yet been studied in detail
with recent X-ray observatories. Here, we present results from an analysis of
the X-ray spectral, temporal, and spatial properties of this source and its
environment based on deep observations carried out with the X-ray satellite
{\sl ROSAT}. The derived mean soft X-ray luminosity of MR 2251-178, ~10^{45}
erg/s, places the quasar among the most X-ray luminous AGN in the local
universe.
  The complete results of this study appeared in A&A 367, 801 (see
http://www.xray.mpe.mpg.de/~skomossa/).

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The categories of this paper are: econ
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The categories of this paper are: adap-org
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-ex
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The categories of this paper are: cs
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The categories of this paper are: comp-gas
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The categories of this paper are: chem-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: acc-phys
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The categories of this paper are: dg-ga
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The categories of this paper are: cmp-lg
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The categories of this paper are: eess
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The categories of this paper are: hep-th
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The categories of this paper are: q-alg
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The categories of this paper are: alg-geom