What happens when electron degeneracy pressure is being overcome (right before an object turns into a black hole)?

Question

I was wondering about hydrostatic equilibrium (the balance of radially inward and outward forces) in large (i.e. above the Chandrasekhar limit) stars. It is often said that when the gravitational force exceeds any outward forces or pressures, mainly the electron degeneracy pressure I'm thinking, the star collapses into a black hole. But how can this happen without the Pauli exclusion principle being violated?

A similar question: Does black hole formation contradict the Pauli exclusion principle?

The answer by @Siva in that question makes some sense to me, but I don't understand at what point we start our counting of states from the object being a star to a black hole. What happens in the middle? Is there a sharp change?

Answer 1

When the force of gravity overcomes electron degeneracy, the electrons are effectively compressed into the nucleus where they are captured and bound by the nucleus (primarily protons) to form a large neutron mass. At this point, the star is even more dense and the process repeats as more electron-degenerate matter falls in and is bound. Meanwhile, energy is given off and this propels an inflationary pressure that can keep the star from collapsing instantly. Over time, the star cools and all remaining matter is bound by gravitation into a neutron star. This object is composed primarily of degenerate neutron matter. [Should the mass exceed 2-3 times the mass of our sun, this star will collapse into a black hole because gravity will overcome the neutron degeneracy pressure. Recall that neutrons, being fermions, cannot occupy the same energy state. Such a collapse is sudden and produces a supernova explosion from the energy transferred to outer layers by the energy released during collapse. This material can include heavier atoms than iron and seeds the surrounding space with the same stuff of which we and our rich planet are made.]

Answer 2

This answer expands on @Rex' s answer, so please read it to get the complete picture. It expands on the part elementary particles have in a black hole creation.

It is often said that when the gravitational force exceeds any outward forces or pressures, mainly the electron degeneracy pressure I'm thinking, the star collapses into a black hole. But how can this happen without the Pauli exclusion principle being violated? . . .

When the simple hydrogen equation does not hold because the potential has been distorted by the gravitational one, an electron can be captured by a proton. This makes a neutron and an electron neutrino. Neutrinos being weakly interacting escape and the neutrons make a neutron star which continues to collapse towards a black hole , if the mass is large enough. There is no problem with the Pauli exclusion or lepton number at this level. Neutrons are composed of quarks which are charged and also obey the Pauli exclusion principle. When the density due to the gravitational collapse becomes large then the whole will turn into a quark gluon plasma. That is as far as elementary particle interactions have taken us. Research is ongoing.

but I don't understand at what point we start our counting of states from the object being a star to a black hole. What happens in the middle? Is there a sharp change?

The point about a black hole is the total mass, such that it does not allow anything to escape from a certain radius. The quantum mechanical behavior from a certain point on is an effective theory joining quantum mechanics and gravitation, a process that is at the frontier of research. It depends on your definition of sharp. Supernovas are sharp.

Supernovae can be triggered in one of two ways: by the sudden reignition of nuclear fusion in a degenerate star; or by the gravitational collapse of the core of a massive star. In the first case, a degenerate white dwarf may accumulate sufficient material from a companion, either through accretion or via a merger, to raise its core temperature, ignite carbon fusion, and trigger runaway nuclear fusion, completely disrupting the star. In the second case, the core of a massive star may undergo sudden gravitational collapse, releasing gravitational potential energy that can create a supernova explosion.

Answer 3

It's hard to bottle up quarks because they'll explode, they want to work with nuclear forces to be matter. So I say the singularity takes the degeneracy forces and nuclear forces with it and it becomes a powerful repulsive force bottled up. And a black hole is a bottle. And right after that neutron star collapsed, you don't say gravity won and nuclear forces lost. You say it's still an intense battle, gravity versus primordial matter repulsive forces pushing outward, and gravity is only winning at the moment by a score of 3 solar masses and 1 gram against 3 solar masses. A power struggle between primordial matter pushing out and gravity pushing down, a singularity ready to explode if only gravity's grip were released.