Institut für Astronomie und Astrophysik

Abteilung Astronomie

Preprint 11a/98

NEW INSIGHT INTO AGN BY COMBINING SPECTRAL AND TIMING INFORMATION

R. Staubert, J. Wilms, K. Pottschmidt

Institut für Astronomie und Astrophysik, Astronomie, Universität Tübingen, Waldhäuser Str. 64, D-72076 Tübingen, Germany

3rd Integral Symposium - The Extreme Universe, in press

Abstract. A case is made for combining spectral and timing analysis of X­ray data in order to better understand the physics at work in Active Galactic Nuclei (AGN). In analysing X­ray light curves from long EXOSAT ME observations of a sample of AGN with a new technique (assuming a stochastic behaviour of the sources) we determine characteristic variability time constants and find that there is a significant correlation with the 2-10keV spectral index (König et al. 1997). This establishes a relationship between the photon index of the X­ray spectrum, and the fastness of the variability. Similar relations have been noted between the photon index and the variability amplitude (Green et al. 1993, Fiore et al. 1998).

Key words: X-rays: galaxies; spectral analysis; timing analysis; variability

Paper (31k gzip'ed Postscript including figures)

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Jürgen Barnstedt (barnstedt AT astro.uni-tuebingen.de) Last updated 11-Dec-1998