Core-collapse supernova simulations in one and two dimensions: comparison of codes and approximations

Abstract

We present spherically symmetric (1D) and axisymmetric (2D) supernova\nsimulations for a convection-dominated 9 Msun and a 20 Msun progenitor that\ndevelops violent activity by the standing-accretion-shock instability (SASI).\nWe compare in detail the Aenus-Alcar code, which uses fully multidimensional\ntwo-moment neutrino transport with an M1 closure, with a ray-by-ray-plus (RbR+)\nversion of this code and with the Prometheus-Vertex code that employs RbR+\ntwo-moment transport with a Boltzmann closure. Besides testing consequences of\nignored non-radial neutrino-flux components in the RbR+ approximation, we also\ndiscuss the influence of various transport ingredients applied or not applied\nin recent literature, namely simplified neutrino-pair processes,\nneutrino-electron scattering, velocity-dependent and gravitational-redshift\nterms, and strangeness and many-body corrections for neutrino-nucleon\nscattering. Alcar and Vertex show excellent agreement in 1D and 2D despite a\nslightly but systematically smaller radius (~1km) and stronger convection of\nthe proto-neutron star with Alcar. As found previously, the RbR+ approximation\nis conducive to explosions, but much less severely in the convection-dominated\n9 Msun case than in the marginally exploding 20 Msun model, where the onset\ntime of explosion also exhibits big stochastic variations, and the RbR+\napproximation has no distinctly stronger supportive effect than simplified pair\nprocesses or strangeness and many-body corrections. Neglecting\nneutrino-electron scattering has clearly unfavorable effects for explosions,\nwhile ignoring velocity and gravitational-redshift effects can both promote or\ndelay the explosion. The ratio of advection timescale to neutrino-heating\ntimescale in 1D simulations is a sensitive indicator of the influence of\nphysics ingredients on explosions also in multidimensional simulations.\n