What mechanism is responsible for reigniting the stalled shock wave into a full catastrophic explosion?
Neutrino heating behind the stalled shock wave.
After the initial shock stalls upon encountering denser infalling material, the mechanism required to transform the implosion into a successful explosion relies on focusing energy directly where it can do the most work—behind the stalled front. While most neutrinos generated during neutronization escape harmlessly, a small, but critically significant fraction of the outward-streaming neutrinos from the nascent neutron star deposit their energy into the material trapped just behind the stagnant shock wave. This process, known as neutrino heating, provides the necessary thermal energy input to reignite the shock, allowing it to propagate outward and cause the star to explode as a visible supernova.
