Could dark matter be neutrinos? I'm wondering, neutrinos are weakly interacting, but they do respond to gravity. So has anyone calculated how far out of a galaxy a typical galactiaclly produced neutrino would travel before coming back into the galaxy? Are some galactically produced neutrinos gravitationally bound to their galaxy?I suppose that they would move very slowly at the outer edge of a galaxy, and very fast near the center. So most of them would spend most of their time at the edges, like dark matter, right?