Oscillation and future detection of failed supernova neutrinos from a black-hole-forming collapse

Recently, stellar collapse involving black-hole formation from massive stars is suggested to emit enormous fluxes of neutrinos on par with ordinary core-collapse supernovae. We investigate their detectability for the currently operating neutrino detector, SuperKamiokande. Neutrino oscillation is also taken into account for the evaluation. We find that the event number is larger than or comparable to that of supernova neutrinos and, hence, black-hole formation is also a candidate for neutrino astronomy. Moreover, we find that the event number depends dominantly on the equation of state used in the computations of the black-hole formation. This fact implies that the detection of neutrinos emitted from the black hole progenitors is very valuable to probe the properties of the equation of state for hot and/or dense matter.