Pre-Supernova Alert System for Super-Kamiokande

TL;DR

This paper discusses the development of a pre-supernova alert system using the Super-Kamiokande detector with gadolinium, capable of providing early warnings of supernovae by detecting neutrinos emitted during the star's final burning phases.

Contribution

It introduces a novel neutrino detection technique for early supernova alerts using SK-Gd, including sensitivity analysis and future prospects for improved detection capabilities.

Findings

High-confidence alerts for Betelgeuse could be issued up to nine hours before collapse.

Enhanced detection sensitivity due to gadolinium addition improves early warning potential.

The system demonstrates the feasibility of pre-supernova neutrino detection with current and future SK-Gd phases.

Abstract

In 2020, the Super-Kamiokande (SK) experiment moved to a new stage (SK-Gd) in which gadolinium (Gd) sulfate octahydrate was added to the water in the detector, enhancing the efficiency to detect thermal neutrons and consequently improving the sensitivity to low energy electron anti-neutrinos from inverse beta decay (IBD) interactions. SK-Gd has the potential to provide early alerts of incipient core-collapse supernovae through detection of electron anti-neutrinos from thermal and nuclear processes responsible for the cooling of massive stars before the gravitational collapse of their cores. These pre-supernova neutrinos emitted during the silicon burning phase can exceed the energy threshold for IBD reactions. We present the sensitivity of SK-Gd to pre-supernova stars and the techniques used for the development of a pre-supernova alarm based on the detection of these neutrinos in SK, as well as prospects for future SK-Gd phases with higher concentrations of Gd. For the current SK-Gd phase, high-confidence alerts for Betelgeuse could be issued up to nine hours in advance of the core-collapse itself.