Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: ROSAT PSPC observations of the infrared quasar IRAS 13349+2438: evidence
  for a warm absorber with internal dust   We present spatial, temporal and spectral analyses of ROSAT Position
Sensitive Proportional Counter (PSPC) observations of the infrared loud quasar
IRAS 13349+2438. IRAS 13349+2438 is the archetypal highly-polarized radio-quiet
QSO and has an optical/infrared luminosity of about 2E46 erg/s. We detect
variability in the ROSAT count rate by a factor of 4.1 in about one year, and
there is also evidence for about 25 per cent variability within one week. We
find no evidence for large intrinsic cold absorption of soft X-rays. These two
facts have important consequences for the scattering-plus-transmission model of
this object which was developed to explain its high wavelength-dependent
polarization and other properties. The soft X-ray variability makes electron
scattering of most of the soft X-rays difficult without a very peculiar
scattering mirror. The lack of significant intrinsic cold X-ray absorption
together with the large observed E(B-V) suggests either a very peculiar system
geometry or, more probably, absorption by warm ionized gas with internal dust.
There is evidence for an ionized oxygen edge in the X-ray spectrum. IRAS
13349+2438 has many properties that are similar to those of the Osterbrockian
`narrow-line' Seyfert 1s.

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The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
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The categories of this paper are: plasm-ph
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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: math-ph
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The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th