ON THE DEPENDENCE OF THE IRON K-LINE PROFILES WITH LUMINOSITY IN ACTIVE GALACTIC NUCLEI

We present evidence for changes in the strength and profile of the iro n K alpha line in active galactic nuclei (AGNs), based on X-ray observ ations with ASCA. There is a clear decrease in the strength of the lin e with increasing luminosity. This relation is not due solely to radio power, as it persists when only radio-quiet AGNs are considered and t herefore cannot be fully explained by relativistic beaming. In additio n to the change in strength, the line profile also appears to be diffe rent in higher luminosity sources. We discuss these results in terms o f a model where the accretion disk becomes ionized as a function of th e accretion rate.