A convective trigger for supernova explosions

The shock wave that stalls within ∼10 ms of its creation during the collapse and bounce of the core of a massive star leaves behind it unstable lepton and entropy profiles that can drive a violent Rayleigh-Taylor-like overturn. Coupling two-dimensional hydrodynamics with independent one-dimensional neutrino transport in 100 angular bins, we demonstrate the possible existence of a convective boost in the neutrino luminosities that can ignite a supernova explosion. While the shock-imposed negative entropy gradient drives the early convection, neutrino heat transfer can smooth it within 15 ms. However, the negative lepton gradient, generically created at shock break-out, is not smoothed and is reponsible for vigorous mantle overturn just interior to the early entropy spike. Within 30 ms of shock decay, a model that in two-dimensions with no transport does not explode and in one dimension with transport does not explode, does explode in two dimensions with transport. The instability dredges up heat, feeds the neutrinospheres, and accelerates the rate of energy and lepton loss in the mantle by up to a factor of 2.