Supernova Simulations with Boltzmann Neutrino Transport: A Comparison of Methods

Accurate neutrino transport has been built into spherically symmetricsimulations of stellar core collapse and postbounce evolution. The results ofsuch simulations agree that spherically symmetric models with standardmicrophysical input fail to explode by the delayed, neutrino-driven mechanism.Independent groups implemented fundamentally different numerical methods totackle the Boltzmann neutrino transport equation. Here we present a direct anddetailed comparison of such neutrino radiation-hydrodynamical simulations fortwo codes, Agile-Boltztran of the Oak Ridge-Basel group and Vertex of theGarching group. The former solves the Boltzmann equation directly by animplicit, general relativistic discrete angle method on the adaptive grid of aconservative implicit hydrodynamics code with second-order TVD advection. Incontrast, the latter couples a variable Eddington factor technique with anexplicit, moving-grid, conservative high-order Riemann solver with importantrelativistic effects treated by an effective gravitational potential. Thepresented study is meant to test both neutrino radiation-hydrodynamicsimplementations and to provide a data basis for comparisons and verificationsof supernova codes to be developed in the future. Results are discussed forsimulations of the core collapse and post-bounce evolution of a 13 solar massstar with Newtonian gravity and a 15 solar mass star with relativistic gravity.Comment: 23 pages, 13 figures, revised version, to appear in Ap