Core-Collapse Simulations of Rotating Stars

We present the results from a series of two-dimensional core-collapse simulations using a rotating progenitor star. We find that the convection in these simulations is less vigorous because (1) rotation weakens the core bounce that seeds the neutrino-driven convection and (2) the angular momentum profile in the rotating core stabilizes against convection. The limited convection leads to explosions that occur later and are weaker than the explosions produced from the collapse of nonrotating cores. However, because the convection is constrained to the polar regions, when the explosion occurs it is stronger along the polar axis. This asymmetric explosion may explain the polarization measurements of core-collapse supernovae. These asymmetries also provide a natural mechanism to mix the products of nucleosynthesis out into the helium and hydrogen layers of the star. We also discuss the role the collapse of these rotating stars plays in the generation of magnetic fields and neutron star kicks. Given a range of progenitor rotation periods, we predict a range of supernova energies for the same progenitor mass. The critical mass for black hole formation also depends upon the rotation speed of the progenitor.