Pre-supernova neutrino emission from massive stars and their detection

Recent progress of neutrino detectors makes it possible to detect pre-SN neutrinos, which are emitted from the core of massive stars before supernova explosions. Pre-SN neutrino observations will become an alarm for supernovae. We hence calculate the number luminosity and energy spectra of pre-SN neutrinos from the 15 M ⊙ progenitor based on the state-of-the-art calculations of massive stars. We find that the number luminosity of v e ’s is L N v ∼ 10 55 , 10 57 s − 1 before core collapse and core bounce, respectively, whereas that of v ¯ e ’s becomes largest around core collapse L N v ∼ 10 53 s − 1 . We then estimate the number of neutrino events at neutrino detectors taking neutrino oscillations into the obtained luminosities and spectra. We find that an alarm is issued a few days before the explosion by detecting v ¯ e ’s at liquid-scintilation type detectors if the progenitor is located at 200 pc. Finally, we perform a systematic study of pre-SN neutrino emission for 7 progenitor models with different initial masses. We find that the difference of the number luminosities is ~ 1 order and the dependence of the initial mass have to be taken into the theoretical predictions of pre-SN neutrino observations.