Imprint of explosion mechanism on supernova relic neutrinos

The spectrum and event rate of supernova relic neutrinos are calculated, taking into account the dependence on the time it takes for the shock wave in supernova cores to revive. The shock revival time should depend on the still unknown explosion mechanism of collapse-driven supernovae. The contribution of black-hole-forming failed supernovae is also considered. The total event rate is higher for models with a longer shock revival time and/or a failed-supernova contribution. The hardness of the spectrum does not strongly depend on the shock revival time, but the spectrum becomes hard owing to the failed supernovae. Therefore, the shock-revival-time dependence of supernova relic neutrinos has different systematics from the fractions of failed supernovae.