IRON LINE-PROFILES INCLUDING EMISSION FROM WITHIN THE INNERMOST STABLE ORBIT OF A BLACK-HOLE ACCRETION DISC

Reynolds & Begelman have recently proposed a model in which the broad and extremely redshifted iron line seen during a deep minimum of the l ight curve of the Seyfert 1 galaxy MCG-6-30-15 originates from matter spiralling into a Schwarzschild black hole, contrary to previous claim s that the black hole may be spinning rapidly. Here we calculate in de tail the X-ray spectrum produced by their model using the full reflect ed continuum emission, including absorption features. This calculation takes into account the Doppler and relativistic effects. For the rang e of parameters that we consider, we find that the spectrum should sho w a large photoelectric absorption edge of iron, which is not seen in the data. The absorption edge is a consequence of the line-emitting ma tter within the innermost stable orbit being highly ionized, and is la rgely independent of the parameters chosen for the model. If we restri ct our attention to the 3-10 keV band we may effectively remove this a bsorption edge by fitting a steeper power law, but this results in a s ignificant underprediction of the 0.4-0.5 keV flux. We conclude that t he data on MCG-6-30-15 are more consistent with the Kerr than the Schw arzschild model.