Broadening of the Iron emission line in MCG-6-30-15 by Comptonization

We show that the Iron K emission line from MCG-6-30-15 could be broadened due to Comptonization by a surrounding highly ionized cloud with radius ∼ 10 cms. We calculate the temperature of the cloud to be ∼ 0.21 keV, provided a reasonable estimate of the UV flux is made. The X-ray/γ-ray emission observed from the source is compatible with this model. Such a cloud should be highly ionized and strong absorption edges are not expected from the source (Fabian et al. 1995). For a 10M black hole the size of the could corresponds to about 300 Schwarzschild radius. The intrinsic line could then be emitted far from the black hole and gravitational red-shift and Doppler effects would be negligible. If the black hole mass is much larger than 10M , gravitational/Doppler red-shifts would also contribute significantly to the broadening. We argue that the broad red wing observed in the source does not by itself imply emission from regions close ( R < 5rs) to the black hole. However, Comptonization cannot produce a double peak. The presence of such a feature is a clear sign of inner disk emission influenced by gravitational and Doppler effects, perhaps broadened by the Comptonization. We note that simultaneous broad band (2-100 keV) study of this source can also reveal (or rule out) the presence of such a Comptonizing cloud. Subject headings: accretion disks—black hole physics—galaxies:individual (MCG-6-30-15)—galaxies:Seyfert—line:profile