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EnglishWe 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 (?~ 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.
| Titolo: | Arakelian 564: An XMM-Newton view |
| Autore/i: | VIGNALI, CRISTIAN; Brandt W. N.; Boller T.h.; Fabian A. C.; Vaughan S. |
| Autore/i Unibo: | |
| Anno: | 2004 |
| Rivista: | |
| Digital Object Identifier (DOI): | http://dx.doi.org/10.1111/j.1365-2966.2004.07269.x |
| Abstract: | 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 (?~ 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. |
| Data prodotto definitivo in UGOV: | 2005-10-08 18:32:02 |
| Appare nelle tipologie: | 1.01 Articolo in rivista |
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http://hdl.handle.net/11585/12022
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