  We discuss constraints on the physics of the inner accretion disk, as well as
the properties of the black hole itself, that can be derived by a detailed
examination of the relativistically broadened spectral features (especially the
fluorescent iron line) in the Seyfert galaxy MCG-6-30-15. To begin with, we
show that spectral models which purport to eliminate the broad iron line in
MCG-6-30-15 by invoking a moderately high ionization absorber are ruled out by
recent high-resolution spectra from the Chandra High Energy Transmission
Gratings. We then discuss the comparison of XMM-Newton data with accretion disk
models. The "standard'' black hole disk model of Novikov, Page and Thorne
supplemented by the so-called local corona assumption fails to produce
sufficient broadening; this indicates that the real accretion disk in
MCG-6-30-15 has significantly more centrally concentrated pattern of X-ray
irradiation that predicted by this model. We discuss two possible resolutions.
Firstly, the inner disk may be energized from torques imposed by magnetic
connections between the disk-proper and either the plunging region or the
rotating event horizon itself. Secondly, X-ray emission from a high-latitude
source (such as would be the case of the X-ray source is actually the base of a
jet) would be gravitationally focused onto the central portions of the disk. We
discuss how spectral variability may be used to examine these possibilities and
highlight the still outstanding mystery concerning the anti-correlation between
the iron line equivalent width and relative normalization of the Compton
reflection hump. We end with a few words about the exciting future of these
studies in the future era of Constellation-X and LISA.
