I’m not smart enough to answer your question. But I wouldn’t mind speculating a little myself on large galactic and even filament scales. I think we’re underestimating how invasive gravity can be on these galactic bodies. There might be far more supermassive black holes out there that seem to have extremely far reaching affects well beyond the galaxies they inhabit, and perhaps their reach, or “waves” not only travel incredibly far, but might be adding to the galactic influences we see on edges of galaxies, galaxy clusters and filament formations/rotations.