What is the immediate physical consequence of the infalling outer layers slamming into the newly formed, incompressible core?

Answer

The impact causes the infalling material to abruptly rebound, generating a shockwave

The collision between the inward-moving material and the stiff, newly formed neutron star initiates a powerful outward-moving shockwave due to the sudden halting and rebound of the falling matter.

What is the immediate physical consequence of the infalling outer layers slamming into the newly formed, incompressible core?
astronomystarsupernovatriggercore collapse