If super massive black holes dilate time for things close to them, to experience time very slowly for everything else... Could this make something akin to a hydraulic jump, or galactic scale heliopause where time runs faster?
AKA the red zone is heavily dilated time, very slow, near the supermassive black hole, and the green zone, time is faster than "normal" ?

Why we think it's weird that the outer arm stars are "moving faster" ?