When space is quiet matter vanishes. Twist a three dimensional wave form and you have a vortex. In a vortex you have both spin and compression or rotation and gravity. Planets and stars are the results of twisted electromagnetic fields forming vortex fields. Galaxies too are immense vortex fields in space.
Black holes are vortex drains returning matter back to empty space.
This article makes it clear that galaxies and black holes go together. Of course, you cannot have a vortex without a drain. Ths website is designed and maintained in cooperation with HelpForMyWebsite.