The supersolid dark matter displaced by a galaxy pushes back, causing the stars in the outer arms of the galaxy to orbit the galactic center at the rate in which they do.
Displaced supersolid dark matter is curved spacetime.
'Astronomers Discover New Galaxy That Is 99.99% Dark Matter' https://www.popularmechanics.com/space/deep-space/a22542/gal...
> "A relatively large fraction of the stars is in the form of very compact clusters, and that is probably an important clue."
The more compact the cluster the greater the displacement of the supersolid dark matter connected to and neighboring the cluster, the greater the displaced supersolid dark matter pushes back and exerts pressure toward the cluster, the faster the stars in the cluster move.
'Scientists Thought All Galaxies Had Dark Matter, but They Just Found One Without It' https://www.smithsonianmag.com/smart-news/galaxy-without-dar...
> "DF2 upends current theories about how galaxies form, which predict that the gravity of dark matter is necessary for early galaxies to hang together."
The reason for the mistaken notion the galaxy is missing dark matter is that the galaxy is so diffuse that it doesn't displace the supersolid dark matter outward and away from it to the degree that the dark matter is able to push back and cause the stars far away from the galactic center to speed up.
It's not that there is no dark matter connected to and neighboring the visible matter. It's that the galaxy has not coalesced enough to displace the supersolid dark matter to such an extent that it forms a halo around the galaxy.
A galaxy's halo is not a clump of dark matter traveling with the galaxy. A galaxy's halo is displaced supersolid dark matter.
