Supernovae, Rotation, and Bipolar Explosions

In this paper, we discuss the possible role of rotation in supernova blast energetics and morphology, and speculate on the origin of Cas A's and SN1987A's ejecta fields. Two 'explosive' phenomena may be associated with most core collapses, the neutrino-driven supernova itself and an underenergetic jet-like ejection that follows. The latter may be a magnetic wind that easily penetrates the debris created by the much more energetic supernova. We speculate that many core-collapse supernova remnants should have sub-dominant jet-like features. In Cas A, we associate this sub-dominant collimated wind with the 'jet/counter-jet' structure observed. We suggest that the actual Cas A explosion itself is at nearly right angles to this jet, along a rotation axis that coincides with the bulk of the ejecta, the iron lobes, and the putative direction of motion of the point source. It may be that when rotation becomes sufficiently rapid that the strong-neutrino-driven-supernova/weak-jet duality switches to a strong-MHD-jet scenario that might be associated with hypernovae, and in some cases GRBs. Finally, we present a calculation using a new 2D multi-group, flux-limited radiation/hydrodynamics code we have recently developed for the simulation of core-collapse supernovae. We discuss the rotation-induced anisotropy in the neutrino radiation field, neutrino heating, and the neutrino flux vectors and speculate on rotation's possible role in the supernova mechanism