Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: XMM-Newton observation of PG 0844 + 349   In a ~ 20 ksec XMM-Newton observation the X-ray transient radio-quiet quasar
PG 0844+349 was found in a historically high state compared to previous X-ray
observations. The quasar showed a featureless spectrum with a strong soft
excess over the extrapolation of a hard power law. Comptonization models or a
broken power law with Gamma_{soft} ~ 2.75, Gamma_{hard} ~ 2.25 and a break
energy of E_{break} ~ 1.35 keV represent acceptable descriptions of the
spectral continuum. In the Comptonization models the temperature of the
Comptonizing gas is considerably lower than generally found in (broad line)
Seyfert galaxies whereas the optical depth is much higher. As a similar
behavior has been seen in NLSy1 galaxies, it might be an indicator of the
different physical conditions in these two classes of AGN. During the
XMM-Newton observation the flux of PG 0844+349 varied achromatically in a
smooth, nearly linear fashion, by ~ 25 % on time scales of a few thousand
seconds, which puts some constraints on current models of Comptonizing
accretion disk coronae.

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The categories of this paper are: adap-org
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The categories of this paper are: nucl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: ao-sci
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
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The categories of this paper are: physics
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-ph
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The categories of this paper are: patt-sol
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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: q-bio
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The categories of this paper are: chao-dyn