Upper limits on the diffuse supernova neutrino flux from the SuperKamiokande data

TL;DR

This paper sets new upper limits on the diffuse supernova neutrino flux using SuperKamiokande data, significantly improving previous constraints across various neutrino types and energy ranges.

Contribution

It provides the most stringent bounds to date on supernova neutrino flux components, covering multiple neutrino flavors and energy intervals, based on extensive SuperKamiokande data analysis.

Findings

Established upper limits on neutrino flux components at 90% C.L.

Improved constraints on nu_e flux over previous SNO limits.

Enhanced bounds on muon and tau neutrino fluxes by four orders of magnitude.

Abstract

We analyze the 1496 days of SuperKamiokande data to put limits on the nue, anti-nue, numu + nutau and anti-numu + anti-nutau components of the diffuse flux of supernova neutrinos, in different energy intervals and for different neutrino energy spectra. By considering the presence of only one component at a time, we find the following bounds at 90% C.L. and for neutrino energy E>19.3$ MeV: Phi_{nue}<73.3-154 cm^-2 s^-1, Phi_{anti-nue} <1.4-1.9 cm^-2 s^-1, Phi_{numu+nutau} <(1.0-1.4) 10^3 cm^-2 s^-1, and Phi_{anti-numu+ anti-nutau} <(1.3-1.8) 10^3 cm^-2 s^-1, where the intervals account for varying the neutrino spectrum. In the interval E = 22.9 - 36.9 MeV, we find Phi_{nue}<39-54 cm^-2 s^-1, which improves on the existing limit from SNO in the same energy window. Our results for numu + nutau and anti-numu + anti-nutau improve by about four orders of magnitude over the previous best constraints from LSD.