Statistics of relativistically broadened FeK alpha lines in AGN

We present preliminary results on the properties of relativistically broadened Fe K alpha lines in a collection of more then 100 Active Galactic Nuclei (AGN) observed by the XMM-Newton EPIC-pn camera. Our main conclusions can be summarized as follows: a) we detect broad lines in about 25% of the sample objects. This fraction increases to 42 +/- 13% if we consider only objects with more than 104 counts in the hard (2-10 keV) band, and to 50 +/- 32% for the small sub-sample (6 objects) of type 1 Piccinotti AGN with optimal XMM-Newton exposure (at least 2 x 105 counts in the hard band); b) we find no significant difference in the detection rate of broad lines between obscured and unobscured AGN; c) the strongest relativistic profiles are measured in low-luminosity (L-X < 10(43) erg s(-1)) AGN; d) Equivalent Widths (EWs) associated with relativistic profiles in stacked spectra are; less than or similar to 150 eV for all luminosity classes; e) models of relativistically broadened iron line profiles (kyrline, Dovciak et al. 2005), which include full relativistic treatment of the accretion disk emission around a Kerr black hole in the strong gravity regime, yield an average disk inclination angle similar or equal to 30 degrees, and a radial dependence of the disk emissivity profile similar or equal to -3. The distribution of EW is very broad, with (log(EW)) = 2.4 and sigma(log(EW)) = 1.4. We estimate that an investment of about 1 Ms of XMM-Newton time would be required to put these results on a sound statistical basis. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.