Modeling core collapse supernovae in 2 and 3 dimensions with spectral neutrino transport

The overwhelming evidence that the core collapse supernova mechanism is inherently multidimensional, the complexity of the physical processes involved, and the increasing evidence from simulations that the explosion is marginal presents great computational challenges for the realistic modeling of this event, particularly in 3 spatial dimensions. We have developed a code scalable to computations in 3 dimensions that couples PPM Lagrangian-with-remap hydrodynamics [1], multigroup flux-limited diffusion neutrino transport [2] (with many improvements), and a nuclear network [3]. The neutrino transport is performed in a "ray-by-ray-plus" approximation, wherein all the lateral effects of neutrinos are included (e.g., pressure, velocity corrections, advection) except lateral transport. A moving radial grid option permits the evolution to be carried out from initial core collapse with only modest demands on the number of radial zones. The inner part of the core is evolved after collapse, along with the rest of the core and mantle, by subcycling the lateral evolution near the center as demanded by the small Courant times. We present results of 2-D simulations of a symmetric and an asymmetric collapse of both a 15 and an 11 M circle dot progenitor. In each of these simulations we have discovered that once the oxygen-rich material reaches the shock there is a synergistic interplay between the reduced ram pressure, the energy released by the burning of the shock-heated oxygen-rich material, and the neutrino energy deposition that leads to a revival of the shock and an explosion.