  We study the temporal and spectral evolution of the radio flares detected
from the relativistic ejecta in the microquasar GRS 1915+105, and develop a
model which suggests that these flares are due to synchrotron radiation of
relativistic electrons suffering adiabatic and radiative energy losses in
fastly expanding plasmoids (radio clouds). Analytical solutions to the kinetic
equation for the electrons in expanding magnetized clouds are found. Detailed
comparison of the calculated radio fluxes with the ones detected from the
prominent flare of GRS 1915+105 during March/April 1994 provides conclusive
information on the basic parameters in the ejecta, such as the absolute values
and temporal evolution of the magnetic field, speed of expansion, the rate of
continuous injection of radio electrons into and their energy-dependent escape
from the clouds, etc. The data of radio monitoring of the pair of resolved
ejecta enable determination of parameters of the bulk motion of counter ejecta
and the degree of asymmetry between them, and contain important information on
the prime energy source for the accelerated electrons. Assuming that the
electrons might be accelerated up to very high energies, we calculate the
fluxes of synchrotron radiation up to hard X-rays/soft gamma-rays, and of the
inverse Compton GeV/TeV gamma-rays expected during radio flares, and discuss
the implications which could follow from either positive detection or flux
upper limits of these energetic photons.
