Doesn't observation show that the outer edges of a galaxy rotates much faster than a spinning star cluster would? So there needs to be more mass concentration t

Doesn't observation show that the outer edges of a galaxy rotates much faster than a spinning star cluster would? So there needs to be more mass concentration towards the outer edges (or even haloed around the galaxy) to match observation. In other words: should a simulation like this also contain transparent dots spread out with a different density function than the visible dots, to account for dark matter?