Inelastic neutrino-helium scatterings and standing accretion shock instability in core-collapse supernovae

We present the results of numerical experiments, in which we have investigated the influence of the inelastic neutrino-helium interactions on the standing accretion shock instability supposed to occur in the postbounce supernova core. The axisymmetric hydrodynamical simulations of accretion flows through the standing accretion shock wave onto the proto-neutron star show that the interactions are relatively minor and the linear growth of the shock instability is hardly affected. The extra heating given by the inelastic reactions becomes important for the shock revival after the instability enters the nonlinear regime, but only when the neutrino luminosity is very close to the critical value at which the shock would be revived without the interactions. We have also studied the dependence of the results on the initial amplitudes of perturbation and the temperatures of mu and tau neutrinos.