Combined Pre-Supernova Alert System with Kamland and Super-Kamiokande

Preceding a core-collapse supernova, various processes produce an increasingamount of neutrinos of all flavors characterized by mounting energies from theinterior of massive stars. Among them, the electron antineutrinos arepotentially detectable by terrestrial neutrino experiments such as KamLAND andSuper-Kamiokande via inverse beta decay interactions. Once these pre-supernovaneutrinos are observed, an early warning of the upcoming core-collapsesupernova can be provided. In light of this, KamLAND and Super-Kamiokande havebeen monitoring pre-supernova neutrinos since 2015 and 2021, respectively.Recently, we performed a joint study between KamLAND and Super-Kamiokande onpre-supernova neutrino detection. A pre-supernova alert system combining theKamLAND detector and the Super-Kamiokande detector is developed and put intooperation, which can provide a supernova alert to the astrophysics community.Fully leveraging the complementary properties of these two detectors, thecombined alert is expected to resolve a pre-supernova neutrino signal from a 15M_⊙ star within 510 pc of the Earth, at a significance levelcorresponding to a false alarm rate of no more than 1 per century. For aBetelgeuse-like model with optimistic parameters, it can provide early warningsup to 12 hours in advance.