Search for supernova neutrinos and constraint on the galactic star formation rate with the KamLAND data

TL;DR

This study uses KamLAND data to search for supernova neutrinos, setting upper limits on supernova rates and the galactic star formation rate, with no neutrino clusters detected over nearly two decades.

Contribution

It provides the first long-term neutrino-based constraints on supernova occurrence and galactic star formation rate, improving previous limits with extensive data analysis.

Findings

No neutrino clusters detected in 18 years of data.

Upper limit on supernova rate: 0.15 per year.

Upper limit on galactic star formation rate: 17.5–22.7 solar masses per year.

Abstract

We present the results of a search for core-collapse supernova neutrinos, using long-term KamLAND data from 2002 March 9 to 2020 April 25. We focus on the electron antineutrinos emitted from supernovae in the energy range of 1.8--111 MeV. Supernovae will make a neutrino event cluster with the duration of $\sim$10 s in the KamLAND data. We find no neutrino clusters and give the upper limit on the supernova rate as to be 0.15 yr$^{-1}$ with a 90% confidence level. The detectable range, which corresponds to a >95% detection probability, is 40--59 kpc and 65--81 kpc for core-collapse supernovae and failed core-collapse supernovae, respectively. This paper proposes to convert the supernova rate obtained by the neutrino observation to the Galactic star formation rate. Assuming a modified Salpeter-type initial mass function, the upper limit on the Galactic star formation rate is <(17.5--22.7) $M_{\odot} \mathrm{yr}^{-1}$ with a 90% confidence level.