Core collapse supernovae: Modeling requirements and surprises

Past modeling efforts have illuminated that core collapse supernovae may be neutrino driven, MHD driven, or both, but uncertainties in the current models prevent us from being able to answer even this most basic question. Certain, however, is the need for multifrequency, and ultimately multifrequency and multiangle, neutrino transport. Moreover, terms in the neutrino transport equations that describe "observer corrections," such as angular aberration and frequency shift, are critical and cannot be neglected, and for massless neutrinos, global conservation of both lepton number and lab-frame specific neutrino energy must be maintained. Recent simulations in three dimensions of the stationary accretion shock instability (SASI) have also clearly demonstrated that two-dimensional models, constrained by axisymmetry, are limited and that three dimensional simulations will yield many surprises, some of them quite remarkable. Two areas that have not received as much attention in the past, neutrino mixing and magnetic fields, must be explored and may yield many additional surprises. The recent discovery that neutrino-neutrino interactions may result in deep neutrino mixing for both neutrinos and antineutrinos, across the energy spectrum, and possibly maximal mixing, must be explored in the context of detailed numerical simulations, and parameterized studies of core collapse supernovae with magnetic fields have produced a variety of results, depending on initial magnetic field configurations and strength, that now beg for detailed neutrino radiation magnetohydrodynamics simulations with multifrequency neutrino transport, especially in three dimensions, to determine which possibilities are realized in Nature.