Presupernova neutrino events relating to the final evolution of massive stars

TL;DR

This paper explores how current and future neutrino detectors can observe presupernova neutrinos from nearby massive stars, providing insights into their final evolution and burning processes before supernova explosions.

Contribution

It demonstrates the potential for detecting and analyzing presupernova neutrino signals to understand stellar core processes and improve supernova early warning systems.

Findings

Neutrino detectors can observe hundreds of events from stars at ~200 pc.

Detection of neutrino rate decreases can indicate shell burning activities.

Time variation in neutrino signals reveals details of stellar core evolution.

Abstract

When a supernova explosion occurs in neighbors around hundreds pc, current and future neutrino detectors are expected to observe neutrinos from the presupernova star before the explosion. We show a possibility for obtaining the evidence for burning processes in the central region of presupernova stars though the observations of neutrino signals by current and future neutrino detectors such as KamLAND, JUNO, and Hyper-Kamiokande. We also investigate supernova alarms using neutrinos from presupernova stars in neighbors. If a supernova explodes at ~ 200 pc, future 20 kton size liquid scintillation detectors are expected to observe hundreds neutrino events. We also propose a possibility of the detection of neutrino events by Gd-loaded Hyper-Kamiokande using delayed $\gamma$-ray signals. These detectors could observe detailed time variation of neutrino events. The neutrino emission rate increases by the core contraction in the final evolution stage. However, the O and Si shell burnings suppress the neutrino emission for a moment. The observed decrease in the neutrino event rate before hours to the explosion is possibly evidence for the shell burnings. The observations of detailed time evolution of presupernova neutrino events could reveal properties of burning processes in the central region of presupernova stars.