Cosmic balls of trapped neutrinos

Fermions trapped inside a closed domain wall may cool to degeneracy and form a long-lived structure. In the context of spontaneous left-right-symmetry breaking, we show that trapped right-handed neutrinos cool due to annihilations to electron-positron pairs if the initial temperature is less than 0.21$m_e$. The surface tension of the wall must be less than (1.93 TeV${)}^3$. The lifetime of the neutrino ball (NB) is determined by neutrino annihilation to three photons and may be comparable to the age of the Universe. These NB’s are in the ${10}^4$–${10}^7$ solar mass range and radiate γ rays in the few hundred keV range at a rate of ${10}^{40}$–${10}^{44}$ erg/sec range. NB’s die in a ${10}^{56}$–${10}^{59}$ erg electron-positron burst.