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We investigate the enhancement of lepton number, energy, and entropy transport resulting from active-sterile neutrino conversion νe→νs deep in the post-bounce supernova core followed by reconversion νs→νe further out, near the neutrino sphere. We explicitly take account of shock wave and neutrino heating modification of the active neutrino forward scattering potential which governs sterile neutrino production. We find that the νe luminosity at the neutrino sphere could be increased by between ∼10% and ∼100% during the crucial shock reheating epoch if the sterile neutrino has a rest mass and vacuum mixing parameters in ranges which include those required for viable sterile neutrino dark matter. We also find sterile neutrino transport-enhanced entropy deposition ahead of the shock. This "preheating" can help melt heavy nuclei and thereby reduce the nuclear photo-dissociation burden on the shock. Both neutrino luminosity enhancement and preheating could increase the likelihood of a successful core collapse supernova explosion. © 2007 The American Physical Society.

We investigate matter-enhanced Mikheyev-Smirnov-Wolfenstein (MSW) active-sterile neutrino conversion in the νe νs channel in the collapse of the iron core of a presupernova star. For values of sterile neutrino rest mass ms and vacuum mixing angle θ (specifically, 0.5keV5×10-12) which include those required for viable sterile neutrino dark matter, our one-zone in-fall phase collapse calculations show a significant reduction in core lepton fraction. This would result in a smaller homologous core and therefore a smaller initial shock energy, disfavoring successful shock reheating and the prospects for an explosion. However, these calculations also suggest that the MSW resonance energy can exhibit a minimum located between the center and surface of the core. In turn, this suggests a post-core-bounce mechanism to enhance neutrino transport and neutrino luminosities at the core surface and thereby augment shock reheating: (1) scattering-induced or coherent MSW νe→νs conversion occurs deep in the core, at the first MSW resonance, where νe energies are large (∼150MeV); (2) the high energy νs stream outward at near light speed; (3) they deposit their energy when they encounter the second MSW resonance νs→νe just below the proto-neutron star surface. © 2006 The American Physical Society.