BOUNDS ON VERY HEAVY RELIC NEUTRINOS BY THEIR ANNIHILATION IN THE GALACTIC HALO

Taking into account neutrino condensation in the gravitational field o f collapsing matter, we investigate the annihilation of heavy relic ne utrinos in the Galaxy resulting in the generation of cosmic rays. The main neutrino annihilation processes are considered: i.e., nu<(nu)over bar> --> f (f) over bar and nu<(nu)over bar> --> W+W-. The condensati on mechanism allows one to get information on the density distribution in the Galaxy halo without any recourse in an explicit dynamical halo model, and the resulting cosmic ray spectrum provides constraints on the heavy neutrino mass. The comparison of the predicted cosmic ray fl ux with the observed one excludes the heavy neutrino mass range 60 GeV < m(nu) < 115 GeV. Such a restriction leads to a bound on the present energy density of very heavy neutrinos which may be comparable to the corresponding baryonic one only in the range 115 GeV < m(nu) < 300 Ge V. Our approach is valid for multicomponent dark matter and can be use d for species that give even a negligible contribution to the critical cosmological density.