RESONANT SPIN-FLAVOR CONVERSION OF SUPERNOVA NEUTRINOS AND DEFORMATION OF THE ELECTRON ANTINEUTRINO SPECTRUM

The neutrino spin-flavor conversion of <(nu)over bar>(e)<->nu(mu) whic h is induced by the interaction of the neutrino magnetic moment and ma gnetic fields in the collapse-driven supernova is investigated in deta il. We calculate the conversion probability by using the latest precol lapse models of Woosley and Weaver, and also those of Nomoto and Hashi moto, changing the stellar mass and metallicity in order to estimate t he effect of the astrophysical uncertainties. Contour maps of the conv ersion probability are given for all the models as a function of the n eutrino mass-squared difference over neutrino energy (Delta m(2)/E(nu) ) and the neutrino magnetic moment times magnetic fields (mu(nu)B). Th e expected deformation of the <(nu)over bar>(e) spectrum can be clearl y seen from these maps, and some qualitative features which will be us eful in future observations are summarized. It is shown that in the so lar metallicity models some observational effects are expected with De lta m(2) = 10(-5)-10(-1) [eV(2)] and mu(nu)greater than or similar to 10(-12)(10(9) G/B-0) [mu(B)], where B-0 is the strength of the magneti c fields at the surface of the iron core, and B-0=10(9) [Gauss] is a r easonable value which is inferred from the observed magnetic fields in white dwarfs. We also find that:although the dependence on the stella r models or stellar mass is not so large, the metallicity of precollap se stars has a considerable effect on this conversion. In lower metall icity stars, strong precession between <(nu)over bar>(e) and nu(mu) oc curs with small Delta m(2)/E(nu) (less than or similar to 10(-8) [eV(2 )/MeV]), and the conversion probability changes periodically with B-0. Such effects may be seen in a supernova in the Large or Small Magella nic Clouds, and should be taken into account when one considers an upp er bound on mu(nu) from the SN 1987A data.