We examine the properties of the Fe emission lines that arise near 6.4 keV in
the ASCA spectra of AGN. Our emphasis is on the Seyfert 1 galaxies where broad
and apparently complex Fe K alpha emission is observed. We consider various
origins for the line but focus on the pros and cons for line emitting accretion
disk models. We develop a simple model of an illuminated disk capable of
producing both X-ray and optical lines from a disk. The model is able to
reproduce the observed Fe K alpha FWHM ratio as well as the radii of maximum
emissivity implied by the profile redshifts. The overall profile shapes however
do not fit well the predictions of our disk illumination model nor do we derive
always consistent disk inclinations for the two lines. We conclude that the
evidence for and against an accretion disk origin for the Fe K alpha emission
is equal at best. The bulk of the data requires a very disparate set of line
fits which shed little light on a coherent physical model. We briefly consider
alternatives to disk emission models and show that a simple bicone model can
reproduce the FE line profiles equally well.Comment: 29 pages, 6 tables, 6 figures. Submitted for publication in the
Astrophysical Journal part