  Possible models for the generation of electromagnetic (EM) radiation during
the coalescence of neutron star-black hole binaries are considered. The mass of
the remnant disk around the black hole during the coalescence of neutron stars
and black holes is calculated by taking into account the equation of state for
neutron stars and the rotation of the binary components before the coalescence.
The parameters of binary systems before the coalescence (the mass ratio, the
component rotation, the neutron star magnetic field) are calculated by the
population synthesis method. The derived mass of the remnant disk around the
black hole after the coalescence is used to estimate the kinetic energy of the
relativistic jet launched by the Blandford-Znajek mechanism. A disk mass of
more than $\sim 0.05 M_\odot$ required for the formation of short gamma-ray
bursts is shown to be obtained in no more than 1-10\% of the coalescences
(depending on the equation of state). Less efficient common envelopes (a large
parameter $\alpha_{CE}$) lead to a noticeably larger percentage of events with
astrophysically interesting EM energy release. For binaries with a large mass
ratio, in which a magnetized neutron star is not subjected to tidal disruption
before the coalescence, the possibility of the formation of an electrically
charged rotating black hole (Wald charge) is considered and estimates of the
maximum EM power released by such a black hole after the coalescence are made.
The conversion of the emitted gravitational waves into electromagnetic ones in
the relativistic lepton plasma generated in coalescing pulsar-black hole
binaries at the pre-coalescence stage is discussed.
