  The possibility of the effect of electromagnetic radiation (hereinafter -
radiation from vacuum) due to the interaction of zero-point vacuum fluctuations
with free charged particles accelerated at relativistic speeds in electric or
magnetic fields is theoretically demonstrated and confirmed by calculations.
The proposed effect is similar to the appearance of radiation in the Lamb shift
effect in the hydrogen atom and the dynamical Casimir effect. However, unlike
these effects, the radiation characteristics depend on the induction of
electric or magnetic fields. Moreover, in order to comply with the law of
conservation of momentum, the braking radiation of charged particles is
considered as the "third body". As opposed to this bremsstrahlung, radiation
from vacuum will not have a preferred direction. Analytical expressions
describing the radiation characteristics were obtained using a semi-classical
method. The calculated values of the energy and intensity of radiation from
vacuum demonstrate the possibility of using optical methods to determine the
characteristics of such radiation in strong electric or magnetic fields. The
results of the work can be used in studies of astrophysical objects with
powerful electric or magnetic fields, as well as in investigations of physical
vacuum states under laboratory conditions.
