  We demonstrate that a X-ray spectrum of a converging inflow (CI) onto a black
hole is the sum of a thermal (disk) component and the convolution of some
fraction of this component with the Comptonization spread (Green's) function.
The latter component is seen as an extended power law at energies much higher
than the characteristic energy of the soft photons. We show that the high
energy photon production (source function) in the CI atmosphere is distributed
with the characteristic maximum at about the photon bending radius, 1.5r_S,
independently of the seed (soft) photon distribution. We show that high
frequency oscillations of the soft photon source in this region lead to the
oscillations of the high energy part of the spectrum but not of the thermal
component. The high frequency oscillations of the inner region are not
significant in the thermal component of the spectrum. We further demonstrate
that Doppler and recoil effects (which are responsible for the formation of the
CI spectrum) are related to the hard (positive) and soft (negative) time lags
between the soft and hard photon energy channels respectively.
