This question already has an answer here:
since the only thing we know about dark matter that it "attracts" and affect our Baryonic matter's momentum and speed, which means that it does have mass of a sort.
so why didn't we witness a darkmatter-darkmatter interactions in form of collisions of celestial bodies like stars, Black holes or other distinct things, what do we know about that?
PS: it would be very helpful for me if someone has an answer can cite it with a paper on the topic. thanks in advance!