I don’t really understand. Dark matter is in most galaxies interacting gravitationally, but not these three. Their idea is that somehow there was a collision event which stripped the galaxies of their dark matter, because the regular matter got tangled up but dark matter somehow didn’t.
But if dark matter is also interacting gravitationally, why wouldn’t it also be tangled up? And is that something we have seen in other collisions ever?
But if dark matter is also interacting gravitationally, why wouldn’t it also be tangled up? And is that something we have seen in other collisions ever?