How are black holes formed by supernovae?
Yes, in the formation of a neutron star the infall is so great that it is compressed to up to 50 % greater than its normal density. In a neutron star, the nuclear force is strong enough to cause a rebound from this compression, which gives an outward push to the remaining outer layers of the stellar interior. However, the rebound is only part of the mechanism by which the supernova generates its energy. The binding energy of a neutron star is much less than that of a non-collapsed stellar core. The tremendous amount of energy generated by the neutron star formation drives the supernova. The same is true with the formation of a black hole, save that the binding energy of the black hole is even less than a neutron star and hence the explosion would be somewhat more energetic. So the formation to a black hole still includes an explosion. Another way of thinking of the same issue: if the rebound was the only source of energy driving the supernova, the surface layers of the star would only
