What causes the outward shock wave that triggers a core-collapse supernova explosion?

Answer

The rebound of outer core layers impacting the neutron degeneracy pressure point

When the inner core halts its freefall against the nuclear density wall, the outer layers of the collapsing core bounce back, generating an outward-moving shock wave.

What causes the outward shock wave that triggers a core-collapse supernova explosion?
physicsgravitystarstellar evolutioncollapse