2 ms·

Stellar collapses, no, but once a black hole has accreted one other stellar body its dragged frame's axis of rotation will be altered by about half. Ten others

Stellar collapses, no, but once a black hole has accreted one other stellar body its dragged frame's axis of rotation will be altered by about half. Ten others and the original spin will have a very small influence. It's unlikely for accreted stars to be in the same galactic orbit, so the accreted stars will be adding to the rotation in the galactic plane.

raattgift 5y ago
Do you really think that? I suggest you try to write down a simple distribution of matter in the far region of the Kerr metric, and the simplest tractable Lagrangian expressed with respect to the angular variables as the generalized coordinates, and see where it takes you as an exercise just for yourself -- a sort of self-diagnostic comparing your intuitions about weak-field systems and what you get as you walk through this sort of exercise (cf. MTW chs 21 & 26, especially exercise 26.1, which seems obviously relevant). (Near region and strong-field work has already been done for you, numerically but recently, in recent work on GW200129_065458 e.g. https://arxiv.org/search/?query=GW200129&searchtype=all&abstracts=show&order=-announced_date_first&size=50 https://arxiv.org/search/?query=GW200129&searchtype=all&abst... and this excellent visualizer https://vijayvarma392.github.io/binaryBHexp/ https://vijayvarma392.github.io/binaryBHexp/ . For extra self-credit you will already be wondering about the final parsec problem, and junction conditions for the previous problem as you adapt the Kerr metric for multiple black holes.)