Future detection of supernova neutrino burst and explosion mechanism

Future detection of a supernova neutrino burst by large underground detectors would give important information for the explosion mechanism of collapse-driven supernovae. We studied the statistical analysis for the future detection of a nearby supernova by using a numerical supernova model and realistic Monte Carlo simulations of detection by the Super-Kamiokande detector. Pile mainly discuss the detectability of the signatures of the delayed explosion mechanism in the time evolution of the (v) over bar(e) luminosity and spectrum. For a supernova at 10 kpc away from the Earth, we find not only that the signature is clearly discernible but also that the deviation of the energy spectrum from the Fermi-Dirac (FD) distribution can be observed. The deviation from the FD distribution would, if observed, provide a test for the standard picture of neutrino emission from collapse-driven supernovae. For the D = 50 kpc case, the signature of the delayed explosion is still observable, but statistical fluctuation is too large to detect the deviation from the FD distribution. We also propose a method for statistical reconstruction of the time evolution of v, luminosity and spectrum from data, by which we can get a smoother time evolution and smaller statistical errors than by a simple, time-binning analysis. This method is useful especially when the available number of events is relatively small, e.g., a supernova in the LMC or SMC. A neutronization burst of v(e)'s produces about five scattering events when D = 10 kpc, and this signal is difficult to distinguish from (v) over bar(e)p events.