Iron line profiles including emission from within the innermost stable orbit of a black hole accretion disc
Abstract
Reynolds & Begelman have recently proposed a model in which the broad and extremely redshifted iron line seen during a deep minimum of the light curve of the Seyfert 1 galaxy MCG-6-30-15 originates from matter spiralling into a Schwarzschild black hole, contrary to previous claims that the black hole may be spinning rapidly. Here we calculate in detail the X-ray spectrum produced by their model using the full reflected continuum emission, including absorption features. This calculation takes into account the Doppler and relativistic effects. For the range of parameters that we consider, we find that the spectrum should show a large photoelectric absorption edge of iron, which is not seen in the data. The absorption edge is a consequence of the line-emitting matter within the innermost stable orbit being highly ionized, and is largely independent of the parameters chosen for the model. If we restrict our attention to the 3-10 keV band we may effectively remove this absorption edge by fitting a steeper power law, but this results in a significant underprediction of the 0.4-0.5 keV flux. We conclude that the data on MCG-6-30-15 are more consistent with the Kerr than the Schwarzschild model.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- October 1998
- DOI:
- 10.1046/j.1365-8711.1998.02058.x
- arXiv:
- arXiv:astro-ph/9808089
- Bibcode:
- 1998MNRAS.300L..11Y
- Keywords:
-
- ACCRETION;
- ACCRETION DISCS;
- BLACK HOLE PHYSICS;
- LINE: PROFILES;
- GALAXIES: INDIVIDUAL: MCG-6-30-15;
- X-RAYS: GENERAL;
- Astrophysics
- E-Print:
- 5 pages with 5 postscript figures. Accepted for publication in MNRAS