  We present Fe Kalpha line profiles from and images of relativistic discs with
finite thickness around a rotating black hole using a novel code. The line is
thought to be produced by iron fluorescence of a relatively cold X-ray
illuminated material in the innermost parts of the accretion disc and provides
an excellent diagnostic of accretion flows in the vicinity of black holes.
Previous studies have concentrated on the case of a thin, Keplerian accretion
disc. This disc must become thicker and sub-Keplerian with increasing accretion
rates. These can affect the line profiles and in turn can influence the
estimation of the accretion disc and black hole parameters from the observed
line profiles. We here embark on, for the first time, a fully relativistic
computation which offers key insights into the effects of geometrical thickness
and the sub-Keplerian orbital velocity on the line profiles. We include all
relativistic effects such as frame-dragging, Doppler boost, time dilation,
gravitational redshift and light bending. We find that the separation and the
relative height between the blue and red peaks of the line profile diminish as
the thickness of the disc increases. This code is also well-suited to produce
accretion disc images. We calculate the redshift and flux images of the
accretion disc and find that the observed image of the disc strongly depends on
the inclination angle. The self-shadowing effect appears remarkable for a high
inclination angle, and leads to the black hole shadow being completely hidden
by the disc itself.
