Neutrinos from SN 1987a. A Puzzle Revisited

TL;DR

This paper proposes that microlensing by an intervening star could explain the timing discrepancy in neutrino detections from SN 1987a, suggesting two separate bursts and resolving observational inconsistencies.

Contribution

It introduces the novel idea that microlensing effects can cause significant variations in neutrino detection timing across different detectors.

Findings

Microlensing can enhance neutrino intensity at one detector by over an order of magnitude.

A two-burst emission model explains the timing differences observed.

Small source size (~100 km) is crucial for the microlensing effect.

Abstract

The smallest of the four detectors which claim to have observed neutrinos from SN 1987a registered the events more than 4 h earlier than the other three ones. This claim is not usually accepted because it is difficult to understand that the other (and larger) detectors did not register any events at the same time. It is shown that microlensing of the neutrinos by a star in-between the supernova (SN) and Earth can enhance the neutrino intensity at the position of one detector by more than an order of magnitude with respect to the other detectors. Such a configuration is improbable but not impossible. Essential for this enhancement is the small source diameter, of order 100 km. So if two bursts of neutrinos were emitted by SN 1987a at a separation of about 4 h it could be explained easily that the smallest detector observed the first burst while the other ones missed it and vice versa.