The role of the equation of state in the "prompt" phase of type II supernovae

We examine the role of the equation of state (EOS) of hot, dense matter in the prompt phase of stellar collapse. In order to achieve this goal, we have carried out radiation hydrodynamic simulations using an adjustable EOS that is consistent with constraints placed on the EOS by neutron star observations, nuclear systematics, and laboratory experiments. Our simulations of stellar collapse show that these constraints restrict the role that the EOS can play in determining the dynamics of shock propagation. We find that certain nuclear force parameters do not substantially affect the dynamics of collapse as strongly as previously believed. In particular, we find that the shock stall radius is practically independent of the compression modulus and symmetry energy when other constaints on the EOS are satisfied. In contrast, the nuclear symmetry energies have more profound effects on the collapse via electron capture, and these effects may be detectable by means of the neutrino signature of a nearby supernova.