X-RAY SPECTRAL STRUCTURE OF THE SEYFERT-GALAXY NGC-6814

We present new and exciting results of a detailed spectral analysis of improved statistical data based on Ginga observations. We show that the overall X-ray spectrum of NGC 6814 rules out the generally favored reflection model as well as a simple power law with an emission line. The spectrum of NGC 6814 has similar features to that of NGC 4151 which is well fitted by a partial covering model. Indeed, we successfully fit the partial covering model to the spectrum of NGC 6814. The main differences between NGC 6814 and NGC 4151 regarding the details of the model are (1) the absorption edge energy of NGC 6814 is around 7.4-8.3 keV (in the rest frame) which indicates the presence of a warm gas, while the edge energy for NGC 4151 indicates a cold gas; (2) the iron emission line energies from NGC 6814 are around 6.46-6.66 keV which are slightly larger than that for NGC 4151 (approximately 6.4 keV); (3) the covering factor of NGC 6814 with a dense (approximately 10(23) H cm-2) gas is around 40%, while a typical value for NGC 4151 is around 80%-90%. Considering those results along with rapid variabilities of the continuum and iron line intensity, the most likely interpretation is that the effects of Doppler shifts from chaotic orbital motion and gravitational and transverse redshifts produce the present iron line and edge energies of NGC 6814.