KamLAND's search for correlated low-energy electron antineutrinos with astrophysical neutrinos from IceCube

TL;DR

This study searched for low-energy electron antineutrinos in KamLAND coinciding with high-energy astrophysical neutrinos from IceCube, finding no significant excess and setting limits on neutrino fluence and luminosity.

Contribution

First combined analysis of KamLAND and IceCube data to constrain low-energy antineutrino emission from astrophysical sources.

Findings

No significant excess of low-energy antineutrinos observed.

Set limits on electron antineutrino fluence from 1.8 MeV to 100 MeV.

Placed a 90% CL limit on the isotropic thermal luminosity of TXS 0506+056.

Abstract

We report the results of a search for MeV-scale astrophysical neutrinos in KamLAND presented as an excess in the number of coincident neutrino interactions associated with the publicly available high-energy neutrino datasets from the IceCube Neutrino Observatory. We find no statistically significant excess in the number of observed low-energy electron antineutrinos in KamLAND, given a coincidence time window of $\pm$500s, $\pm$1,000s, $\pm$3,600s, and $\pm$10,000s around each of the IceCube neutrinos. We use this observation to present limits from 1.8 MeV to 100 MeV on the electron antineutrino fluence, assuming a mono-energetic flux. We then compare the results to several astrophysical measurements performed by IceCube and place a limit at the 90% confidence level on the electron antineutrino isotropic thermal luminosity from the TXS 0506+056 blazar.