背景1
背景2

Physics

Neutrinos from Supernova Burst

A supernova explosion happens when a star at least 8 times more massive than the sun collapses. An enormous amount of energy (more than 99% of energy emitted from the Sun for 4.5 billion years) is released primarily in the form of neutrinos in just 10 seconds.

大マゼラン星雲で発生した超新星SN1987A

Supernova 1987A, which occurred on February 23, 1987. The right figure shows before explosion. (Anglo-Australian Observatory/David Malin)

On February 23, 1987, a supernova explosion occurred in the Large Magellanic Cloud. From this explosion, the supernova neutrinos were detected for the first time. Kamiokande detected 11 events of these neutrinos. This observation confirmed that the theory of supernova explosion was correct and was the dawn of a new era in neutrino astronomy.

超新星1987Aからのニュートリノ観測データ

The 11 points at 0 seconds show the observed events of the supernova1987a neutrinos.

A supernova explosion is expected to occur inside our galaxy once every 10 to 50 years. If such an explosion occurs, Super-Kamiokande is expected to detect about 8,000 neutrinos. We will be able to reveal the mechanism of supernova explosions by analyzing the information of the energy and the arrival time of these neutrinos.

Super-Kamiokande has a real-time supernova alert system which is running all the time in order not to miss a great discovery of the century. If a supernova occurs in the Galaxy, for example, the alert system will immediately get started to analyze data, so that within 1 hour we can announce that the Super-Kamiokande detects a supernova and send information about the detection time, the number of detected neutrinos, and the direction of the supernova etc.. Since the photons are emitted from the collapsed star after neutrinos, optical observatories will detect a supernova after Super-Kamiokande. Therefore, an announcement from Super-Kamiokande will help astronomers in the word to watch the moment of the explosion.