Stars as Laboratories for Fundamental Physics - MPP Theory Group

What Have We Learned from SN 1987A 497
Still, the observation of the prompt ν e burst from a future galactic
SN would allow for a number of interesting conclusions. For example,
one could exclude or find evidence for neutrino oscillations (Sect. 11.4).
Signal dispersion caused by a neutrino mass or other effects which are
discussed below for the cooling-phase signal would be even more significant
for the prompt burst because of its short duration. For example,
the cooling signal with a duration of about 10 s is sensitive to ν e
masses in the 10 eV regime. As the prompt burst is at least 100 times
shorter one is sensitive to a factor of 10 smaller masses, i.e. to m νe in
the eV range.
The (anti)neutrino signal during the prompt burst phase allows one
to decide if the SN consisted of antimatter rather than matter. In
that case one would expect a prompt ν e burst with a scattering cross
section on electrons which is about a factor of 2.4 smaller (Eq. 10.17).
Moreover, ν e ’s are dominantly absorbed by the isotropic ν e p → ne +
reaction and so the prompt burst would cause a substantial isotropic
signal within the first 50 ms. In a matter SN the cooling ν e ’s have
larger energies than the ν e ’s; the reverse for antimatter. Therefore, the
observable ν e signal from the cooling phase would be reduced. In a
detector like Kamiokande one would then expect 6−20% of the total
ν e signal from the prompt burst, in contrast with at most 1% for a
regular matter SN (Barnes, Weiler, and Pakvasa 1987). Of course, in
the foreseeable future one can hope to acquire the relevant data only
from a galactic SN which, no doubt, consists of matter.
13.2.4 Nonobservation of a γ-Ray Burst
No γ rays in conjunction with the SN 1987A neutrino burst were observed
by the solar maximum mission (SMM) satellite which was operational
at the relevant time. Therefore, one can derive some of the most
restrictive limits on neutrino radiative decays as detailed in Sect. 12.4.
13.3 Dispersion Effects
13.3.1 Photons vs. Antineutrinos
The optical sighting of SN 1987A followed the detection of the ν e burst
by only a few hours (Fig. 11.7), a delay which is expected on the basis
of the simple reasoning that some time must pass before the mantle of
a SN “notices” the collapse of the inner core. Hence the two signals
must have propagated through space with an almost identical velocity