Comparative analysis of SN1987A antineutrino fluence

TL;DR

This paper refines the analysis of SN1987A antineutrino data using improved models and considers various factors, demonstrating the stability of the derived neutrino fluence and its consistency with theoretical expectations.

Contribution

It introduces a new simple formula for the signal, improves detector response modeling, and thoroughly assesses the impact of different assumptions on the fluence analysis.

Findings

Most effects on the fluence are negligible

Results are stable across different analysis assumptions

Data are consistent with theoretical models

Abstract

We discuss the electron antineutrino fluence derived from the events detected by Kamiokande-II, IMB and Baksan on February 23, 1987. The data are analysed adopting a new simple and accurate formula for the signal, improving on the previous modeling of the detectors response, considering the possibility of background events. We perform several alternative analyses to quantify the relevance of various descriptions, approximations and biases. In particular, we study the effect of: omitting Baksan data or neglecting the background, using simplified formulae for the signal, modifying the fluence to account for oscillations and pinching, including the measured times and angles of the events, using other descriptions of detector response, etc. We show that most of these effects are small or negligible and argue, by comparing the allowed regions for astrophysical parameters, that the results are stable. We comment on the accordance with theoretical results and on open questions.