Supernova neutrino halo and the suppression of self-induced flavor conversion

Neutrinos streaming from a supernova core occasionally scatter in the envelope, producing a small ``neutrino halo'' with a much broader angle distribution than the primary flux originating directly from the core. Cherry et al. have recently pointed out that, during the accretion phase, the halo actually dominates neutrino-neutrino refraction at distances exceeding some 100 km. However, the multiangle matter effect (which increases if the angle distribution is broader) still appears to suppress self-induced flavor conversion during the accretion phase.