  Recent X-ray observations of Galactic Black Hole Candidates and AGNs and
Seyfert galaxies reveal the broad emission lines in their spectra, which can
arise in the innermost parts of accretion disks. Simulation indicates that at
low inclination angle the line is registered by distant observer with
characteristic two-peak profile. However, at high inclination angles ($> 85
\degr$) two additional peaks arise. This phenomenon was discovered by Matt,
Perola, Stella (1993) using the Schwarzschild black hole metric to analyze such
effect. They assumed that the effect is applicable to a Kerr metric far beyond
of a range of parameters that they exploited. We check and confirm their
hypothesis about such structure of the spectral line shape for a Kerr metric
case. We use no astrophysical assumptions about physical structure of the
emission region except assumption that the region should be narrow enough.
  Positions and heights of these extra peaks drastically depends on both the
radial coordinate of the emitting region (circular hot spot) and the
inclination angle. We find that best conditions to observe this effect are
realized at $\theta > 85\degr$ and $r > 5r_g$ and may exist in microquasars or
low-mass black holes in X-ray binary systems, because there is some precession
(and nutation of accretion disks) with not very long time periods (see, for
example, SS433 binary system). The line profiles for different inclination
angles and radial coordinates are presented. To analyze an influence of disk
models on the spectral line shapes we simulate the line profiles for Shakura --
Sunyaev disk model for accretion disks with the high inclination.

Astrophysics