Supernova explosions and constraints on mass and lifetime of heavy neutrinos

Constraints on mass and lifetime of heavy neutrinos imposed by supernova explosions are investigated. It is found that in the mass range of 10-70 MeV the constraint imposed by supernovae is more stringent than those given by cosmology. Any lifetime in this mass range is almost ruled out by the present constraint imposed by supernovae together with those imposed by high-energy experiments. It is suggested that if heavy neutrinos have mass and lifetime not ruled out by these constraints, the energy released by neutrino decay can induce supernova explosions even if the standard bounce-shock mechanism fails in explosions. (orig.)