Magnetic fields from the early universe may have kept the Milky Way and other galaxies like it from spreading out, which could have helped feed black holes at their centres
Source:
https://www.newscientist.com/article/2244840-the-milky-way-may-have-been-shrunk-down-by-ancient-magnetic-fields/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home