  We present preliminary results of our study of the impact of strong gravity
effects on properties of the high energy radiation produced in accretion flows
around supermassive black holes. We refine a model of the X-ray emission from a
hot optically-thin flow by combining a fully general-relativistic (GR)
hydrodynamical description of the flow with a fully GR description of
Comptonization. We find that emission from a flow around a rapidly rotating
black hole is dominated by radiation produced within the innermost few
gravitational radii, the region where effects of the Kerr metric are strong.
The X-ray spectrum from such a flow depends on the inclination angle of the
line of sight to the symmetry axis, with higher angles characterised by a
harder slope and a higher cut-off energy.
  Under the (reasonable) assumption that the equatorial plane of a rotating
supermassive black hole is aligned with the surrounding torus, these predicted
properties may provide a crucial extension of the unified model of AGNs,
allowing to reconcile the model with systematic trends reported in a number of
studies of the X-ray spectral properties of AGNs (indicating that type 2
objects are harder than type 1 and that the relative amount of the reflected
radiation is larger in the latter). On the other hand, the model with a rapidly
rotating black hole predicts larger apparent luminosities for objects observed
at higher viewing angles, while an opposite property (i.e. type 1 objects being
more luminous than type 2) was revealed in the Integral data.
