Development of an early warning method incorporating pre-supernova neutrino light curves

TL;DR

This paper introduces an advanced early warning method for supernovae that uses the time evolution of pre-supernova neutrino signals, improving warning times while controlling false alarms.

Contribution

It proposes a novel alarm technique incorporating the time evolution of neutrino signals and multiple stellar models, enhancing supernova warning sensitivity.

Findings

Significant increase in warning time over traditional methods

Maintains false alarm rate while improving detection sensitivity

Effective across multiple neutrino detectors and models

Abstract

Massive stars ($M>8\mathrm{M_\odot}$) emit neutrinos known as pre-supernova (pre-SN) neutrinos through thermal and nuclear interactions for cooling the stellar core during the final stage of stellar evolution. Real-time monitoring of their pre-SN neutrino interaction rate offers a crucial opportunity to issue an early warning to a core-collapse supernova. Some neutrino detectors, including KamLAND and Super-Kamiokande already operate pre-SN alarm systems based on a statistically significant excess of the observed event rate over the expected background. To improve alarm sensitivity, we propose an alarm method which incorporates the time evolution of the observed pre-SN neutrino event rate. The method uses a log likelihood ratio test that references multiple theoretical stellar-evolution models and treats the core collapse time as a nuisance parameter to be profiled over. The performance of the proposed method was evaluated using simulated data for the KamLAND, Super-Kamiokande with dissolved Gadolinium (SK-Gd) and their combined analysis. The results demonstrate a significant improvement in the warning time compared to the conventional rate-only method, while maintaining the same false alarm rate.