> Once the black holes merge, the new, now-larger black hole experiences a kick that sends it off in a random direction, and it plows through the gas in the dis

> Once the black holes merge, the new, now-larger black hole experiences a kick that sends it off in a random direction, and it plows through the gas in the disk Hm, I would expect the merged object to move in the same way as the center of mass of the unmerged objects. Where does the extra momentum for this "kick" come from? Is there mass from the surrounding disk thrown in the other direction? Or maybe some relativistic effect? edit: apparently gravitational waves can carry away linear momentum, and that's where the kick comes from[1]. [1]https://astrobites.org/2018/03/08/recoil-detectives-searching-for-black-hole-kicks-using-gravitational-waves/ https://astrobites.org/2018/03/08/recoil-detectives-searchin...