On the inability of Comptonization to produce the broad X-ray iron lines observed in Seyfert nuclei

Abstract

It has recently been suggested that Compton downscattering may give rise to the broad iron lines seen in the X-ray spectra of Seyfert 1 galaxies. This challenges the standard model in which these lines originate from the innermost regions of the black hole accretion disk with Doppler shifts and gravitational redshifts giving rise to the broadened line profile. Here, we apply observational constraints to the Compton downscattering model for MCG-6-30-15 and NGC3516, the two best cases to date of Seyfert galaxies with relativistically broad lines. We show that the continuum source in MCG-6-30-15 required by the constrained model violates the black body limit. In the case of NGC3516, only a very small region of parameter space is compatible with the constraints. Hence, we conclude that the Comptonization model is not a viable one for the broad line seen in these two objects. The accretion disk model remains the best interpretation of these data.

5 pages, 2 postscript figures. Accepted for publication in ApJ. Error corrected in equation (7)

References in corpus (1)

• On the lack of X-ray iron line reverberation in MCG-6-30-15: Implications for the black hole mass and accretion disk structure

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