Sn1987a Revisited after 20 Years: May the Supernova Bang More Than Once?

TL;DR

This paper reanalyzes supernova 1987A data, suggesting the possibility of multiple bursts and questioning the traditional single-collapse model, based on underground detector observations including LSD and Kamiokande.

Contribution

It presents evidence for a second neutrino burst from supernova 1987A, challenging the conventional understanding of a single collapse event.

Findings

LSD detected only one burst at 2h 52min 36.8sec U.T.

Kamiokande observed a second cluster of pulses at 7h 54min 22.2sec U.T.

The second burst lasted 6.2 seconds, indicating a potentially prolonged collapse process.

Abstract

The observations of supernova 1987A in underground detectors are revisited. It is shown that, while the LSD detector in the Mont Blanc Laboratory observed only one burst at 2h 52min 36.8sec U.T., the Kamiokande data show a possible second burst, in addition to the well known one at 7h 35min 33.7sec U.T. This second burst consists of a cluster of seven pulses, well above the energy threshold of the detector, observed during 6.2 seconds starting at 7h 54min 22.2sec U.T. Do these observations imply a long duration of the collapse?