Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Comparison of high and low state X-ray spectra in the Type 1 QSO 2MASS
  0918+2117   When observed by XMM-Newton in 2003 the type 1 QSO 2MASS 0918+2117 was found
to in a low flux state, some ~4-5 times fainter than during an earlier Chandra
observation. The 2-6 keV spectrum was unusually hard, with evidence for a
reflection-dominated continuum, while a soft excess prevented confirmation of
the anticipated low energy absorber. In a second XMM-Newton observation in
2005, the X-ray flux is found to have recovered, with a 2-10 keV continuum
slope now typical of broad-line active galaxy, and clear evidence for low
energy absorption. We find the preferred ionisation state of the absorbing gas
to be low, consistent with the red nucleus and strong optical polarisation of
2MASS 0918+2117. A residual soft excess is of similar spectral form and flux to
that seen in 2003.

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The categories of this paper are: quant-ph
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The categories of this paper are: math-ph
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
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The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
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The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
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The categories of this paper are: solv-int
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The categories of this paper are: plasm-ph
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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-ex
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The categories of this paper are: eess
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The categories of this paper are: patt-sol