Neutrino oscillations and the supernova 1987A signal

We study neutrino oscillations' effect on the interpretation of the supernova (SN) 1987A neutrino signal by means of a maximum-likelihood analysis. We focus on oscillations between bar νe and bar νμ or bar ντ and those mixing parameters that would solve the solar neutrino problem. For the small-angle MSW solution (Δm2≅10-5 eV2, sin22Θ0≅0.007), there are no significant oscillation effects on the Kelvin-Helmholtz cooling signal; we confirm previous values for the neutron-star binding energy and average spectral bar νe temperature. There is marginal overlap between the upper end of the 95.4% C.L. inferred range of left-angle Ebarνe right-angle and the lower end of the range of theoretical predictions. Any admixture of the stiffer bar νμ spectrum by oscillations aggravates the conflict between inferred experimental and predicted theoretical spectral properties. For mixing parameters near the large-angle MSW solution (Δm2≅10-5 eV2, sin22Θ0≅0.7) the oscillations in the SN are adiabatic, but one needs to include the regeneration effect in the Earth which causes the Kamiokande and IMB detectors to observe different bar νe spectra. For the solar vacuum solution (Δm2≅10-10 eV2, sin22Θ0≅1) the oscillations in the SN are nonadiabatic; vacuum oscillations take place between the SN and the detector. If one of the two large-angle solutions were borne out by the upcoming round of solar neutrino experiments, one would conclude that the SN 1987A bar νμ and/or bar νe spectra had been much softer than predicted by current treatments of neutrino transport. copyright 1996 The American Physical Society