Arakelian 564: An XMM-Newton view

Cristian Vignali, W. N. Brandt, Th Boller, A. C. Fabian, Simon Vaughan

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30 Scopus citations


We report on two XMM-Newton observations of the bright narrow-line Seyfert 1 galaxy Ark 564 taken 1 yr apart (2000 June and 2001 June). The 0.6-10 keV continuum is well described by a soft blackbody component (kT ≈ 140-150 eV) plus a steep power law (Γ ≈ 2.50-2.55). No significant spectral changes are observed between the two observations, although the X-ray flux in the second observation is ≈40-50 per cent lower. In both observations, we detect a significant absorption edge at a rest-frame energy of ≈0.73 keV, corresponding to O VII. The presence of the absorption feature is confirmed by a simultaneous Chandra grating observation in 2000 June, although the best-fitting edge threshold is at a slightly lower energy in the Chandra data, possibly because of a different parametrization of the underlying X-ray continuum. We find tentative evidence for a broad iron emission line in the 2000 June observation. The results from an analysis of the power spectral density (PSD) function are also presented. The present XMM-Newton data support the idea that the PSD shows two breaks, although the location of the high-frequency break requires further constraints.

Original languageEnglish (US)
Pages (from-to)854-860
Number of pages7
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
StatePublished - Jan 21 2004

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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