Why doesn't the dark matter halo co-rotate with the luminous disk? What keeps it from falling into the center if not angular momentum?

Question

1. Why doesn't the dark matter halo co-rotate with the luminous disk?

2. What keeps it from falling into the center if not angular momentum?

Answer 1

Because it does not interact much the individual dark matter components (whatever they may be) have no efficient way to shed their energy and end in lower orbits.

They do fall into the center and then fall right back out again, never losing significant amounts of energy.