Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Detection of type-2 quasars in the radio galaxies B3 0731+438 and 3C 257   We present XMM-Newton observations and spectral fitting of two highly
redshift, [OIII]-luminous, narrow-line radio galaxies, B3 0731+438 and 3C 257.
Their X-ray continua are well fitted by a partial covering model with
intrinsically unabsorbed and absorbed powerlaw components. The spectral models
indicate that both objects harbour highly obscured nuclei, with N_H ~ 0.5 - 2 x
10^23 cm^-2. Correcting for this absorption we find large intrinsic
luminosities in the range L_X ~ 0.2 - 1 x 10^45 erg/s. Thus, both sources are
type-2 quasars.

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The categories of this paper are: eess
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The categories of this paper are: q-alg
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The categories of this paper are: hep-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: nlin
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The categories of this paper are: cmp-lg
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The categories of this paper are: dg-ga
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The categories of this paper are: q-bio
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The categories of this paper are: chem-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: stat
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The categories of this paper are: hep-lat
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The categories of this paper are: adap-org
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The categories of this paper are: supr-con