CHANDRA HIGH-ENERGY GRATING OBSERVATIONS OF THE Fe Kα LINE CORE IN TYPE II SEYFERT GALAXIES: A COMPARISON WITH TYPE I NUCLEI

We present a study of the core of the Fe K alpha emission line at similar to 6.4 keV in a sample of type II Seyfert galaxies observed by the Chandra high-energy grating. The sample consists of 29 observations of 10 unique sources. We present measurements of the Fe K alpha line parameters with the highest spectral resolution currently available. In particular, we derive the most robust intrinsic line widths for some of the sources in the sample to date. We obtained a weighted mean full width at half-maximum (FWHM) of 2000 +/- 160 km s(-1) for 8 out of 10 sources (the remaining sources had insufficient signal to noise). From a comparison with the optical emission-line widths obtained from spectropolarimetric observations, we found that the location of Fe K alpha line-emitting material is a factor of similar to 0.7-11 times the size of the optical broad-line region. Furthermore, compared to 13 type I active galactic nuclei (AGNs) for which the best Fe K alpha line FWHM constraints were obtained, we found no difference in the FWHM distribution or the mean FWHM, and this conclusion is independent of the central black hole mass. This result suggests that the bulk of the Fe K alpha line emission may originate from a universal region at the same radius with respect to the gravitational radius, similar to 3 x 10(4) r(g) on average. By examining the correlation between the Fe K alpha luminosity and the [OIV] line luminosity, we found a marginal difference in the Fe K alpha line flux between type I and type II AGNs, but the spread in the ratio of L-Fe to L-[OIV] is about two orders of magnitude. Our results confirm the theoretical expectation that the Fe K alpha emission-line luminosity cannot trivially be used as a proxy of the intrinsic AGN luminosity, unless a detailed comparison of the data with proper models is applied.