Stars as Laboratories for Fundamental Physics - MPP Theory Group

Chapter 13
What Have We Learned from
SN 1987A
The lessons for particle physics from the SN 1987A neutrino burst are
studied. First, neutrinos could have decayed or oscillated into other
states on their way out of the SN core and to us. Second, propagation
effects could have caused a time delay between photons and neutrinos
or between ν e ’s of different energy. Third, nonstandard cooling agents
could have shortened the neutrino burst below its observed duration.
These arguments are applied to a variety of specific cases.
13.1 Introduction
In Chapter 11 the neutrino observations from SN 1987A were discussed
and it was shown that they agree well with standard theoretical
expectations from the core collapse and subsequent explosion of
an evolved massive star. The signal displays several anomalies (time
gap at Kamiokande, anisotropy in both detectors) which render it a
less beautiful specimen of the expected signal characteristics than is
sometimes stated in the literature. Still, in the absence of plausible
alternatives one must accept that the Kamiokande II, IMB, and Baksan
event clusters observed at 7:35 UT on 27 February 1987 represent
the ν e component of the neutrino burst from the core collapse of the
SN 1987A progenitor star rather than some other particle flux, or some
other reaction than the expected dominant ν e p → ne + process.
Accepting this, there is a host of consequences concerning a variety
of fundamental physics issues. The first and simplest set of arguments
is based on the fact that the ν e pulse and perhaps the prompt ν e burst
493