We extend our investigation of magnetic field evolution in three-dimensional flows driven by the stationary accretion shock instability (SASI) with a suite of higher-resolution idealized models of the post-bounce corecollapse supernova environment. Our magnetohydrodynamic simulations vary in initial magnetic field strength, rotation rate, and grid resolution. Vigorous SASI-driven turbulence inside the shock amplifies magnetic fields exponentially; but while the amplified fields reduce the kinetic energy of small-scale flows, they do not seem to affect the global shock dynamics. The growth rate and final magnitude of the magnetic energy are very sensitive to grid resolution, and both are underestimated by the simulations. Nevertheless our simulations suggest that neutron star magnetic fields exceeding 10 14 G can result from dynamics driven by the SASI, even for non-rotating progenitors.

We begin an exploration of the capacity of the stationary accretion shock instability (SASI) to generate magnetic fields by adding a weak, stationary, and radial (but bipolar) magnetic field, and in some cases rotation, to an initially spherically symmetric fluid configuration that models a stalled shock in the post-bounce supernova environment. In axisymmetric simulations we find that cycles of latitudinal flows into and radial flows out of the polar regions amplify the field parallel to the symmetry axis, typically increasing the total magnetic energy by about two orders of magnitude. Nonaxisymmetric calculations result in fundamentally different flows and a larger magnetic energy increase: shearing associated with the SASI spiral mode contributes to a widespread and turbulent field amplification mechanism, boosting the magnetic energy by almost four orders of magnitude (a result which remains very sensitive to the spatial resolution of the numerical simulations). While the SASI may contribute to neutron star magnetization, these simulations do not show qualitatively new features in the global evolution of the shock as a result of SASI-induced magnetic field amplification.Subject headings: supernovae: general -stars: magnetic fields -MHD -methods: numerical IntroductionKey aspects of the core-collapse supernova explosion mechanism remain unknown. It is known that a shock wave forms when the central density of a collapsing massive star ( 8M ⊙ ) exceeds nuclear density: at this point the repulsive short-range nuclear force stiffens the equation of state (EoS), and the resulting core bounce gives rise to a compression wave that steepens into a shock when it reaches the sonic point that separates the subsonically collapsing inner stellar core from the supersonically infalling outer core. As the roughly spherical shock wave propagates radially outward through infalling material it loses energy through dissociation of heavy nuclei and neutrino