ROSAT PSPC observations of the infrared quasar IRAS 13349+2438: Evidence for a warm absorber with internal dust

W. N. Brandt, A. C. Fabian, K. A. Pounds

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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 ≈ 2 × 1046 erg s-1. We detect variability in the ROSAT count rate by a factor of 4.1 in about one year, and there is also evidence for ≈ 25 per cent variability within one week. We find no evidence for large intrinsic absorption of soft X-rays by 'cold' neutral matter. 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 'narrow-line' Seyfert 1s.

Original languageEnglish (US)
Pages (from-to)326-336
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - Dec 1 1996


All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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