ASCA Observations of Fe Kalpha Line Profiles in Seyfert Galaxies

We present new X-ray spectral data for Fe Kalpha lines in five Seyfert galaxies observed recently with the ASCA satellite. NGC 4151, MCG-2-58-22, and IC 4329A were observed during the performance verification phase of the mission; NGC 2992 and MCG-5-23-16 were observed during the AO-1 guest observer phase. We find that all of the Fe Kalpha line energies are consistent with fluorescence of neutral or weakly ionized Fe. The other Fe Kalpha line properties such as intrinsic line width and equivalent width (EW) have a range of values, suggesting that there is not a ubiquitous origin for Fe Kalpha lines in Seyfert galaxies. The inferred Fe Kalpha widths can be strongly affected by uncertainties in the assumed 2--10 keV continuum in cases where ASCA can resolve the emission line. In particular, the widths can change depending on whether and how much Compton reflection is present. For MCG-2-58-22, assuming no reflection, the line is resolved with a FWHM of 33,000(-20,000,+32,000) km s(-1) . This is consistent with the line arising from some portion of the broad line region, but an accretion disk origin is possible. The EW of ~ 340 eV is larger than expected for an accretion disk, but would be allowed if the disk were at least weakly ionized. In NGC 2992, the line is unresolved (FWHM <5,000 km s(-1) ). The large EW of ~ 500 eV suggests that this line arises from an extended reprocessing region. For IC 4329A we prefer a reflection model and find the Fe Kalpha line is resolved with a FWHM of ~ 17,000 km s(-1) and an EW of ~ 100 eV, consistent with originating in a neutral accretion disk. The line profile appears asymmetric with a possible red wing. Finally, in MCG-5-23-16 and NGC 4151, the Fe Kalpha lines are complex, with both narrow and broad components, although the ``broad'' component in NGC 4151 is more likely the result of continuum complexity between 5 and 10 keV.