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Preprint 02f/02


S. Benlloch (1), J. Wilms (1), R. A. Edelson (2), T. Yaqoob (3;4), and R. Staubert (1)

(1) Institut für Astronomie und Astrophysik, Astronomie, Universität Tübingen, Sand 1, D-72076 Tübingen, Germany
(2) University of California, Los Angeles, Department of Astronomy, Los Angeles, CA 90095-1562
(3) Laboratory for High Energy Astrophysics, NASA Goddard Space Flight Center, Greenbelt, MD 20771
(4) Johns Hopkins University, Department of Physics and Astronomy, Homewood Campus, 3400 North Charles Street, Baltimore, MD 21218

in: New Visions of the X-ray Universe in the XMM-Newton and Chandra Era, eds. F. Jansen & TBD, ESA SP-488, 2002


We discuss methods to compute signi cance levels for the existence of quasi-periodic oscillations (QPOs) in Ac- tive Galactic Nuclei (AGN) which take the red noise char- acter of the X-ray lightcurves of these objects into account. Applying epoch folding and periodogram analysis to the XMM-Newton observation of the Seyfert galaxy Mrk 766, a possible QPO at a timescale of 4200 s has been reported. Our computation of the signi cance of this QPO, however, shows that it is not significant at the 95% level, but rather may be an artifact of the red noise process.

Key words: accretion disks - galaxies: individual (Mrk 766) - galaxies: Seyferts - X-rays: galaxies

Paper (76k gzip'ed Postscript including figures)

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