  The majority of Active Galactic Nuclei (AGN) observed by XMM-Newton reveal
narrow Fe K-alpha lines at ~ 6.4 keV, due to emission from cold (neutral)
material. There is an X-ray Baldwin effect in Type I AGN, in that the
equivalent width of the line decreases with increasing luminosity, with
weighted linear regression giving EW ~ L^{-0.17+/-0.08} (Spearman Rank
probability of > 99.9%). With current instrumental capabilities it is not
possible to determine the precise origin for the narrow line, with both the
Broad Line Region and putative molecular torus being possibilities. A possible
explanation for the X-ray Baldwin effect is a decrease in covering factor of
the material forming the fluorescence line.
