First you need to forget about the dark stuff and think of charge and frequency.
Our Sun is a very large ball of plasma made by hydrogen and helium, it fills the solar system with charged hydrogen and helium particals. No dark matter or energy even thow dark matter is effected by gravity.
Much the same for our galaxy,it is also packed with charged hydrogen and helium, but o ce past the galaxys protective outer shell.
This shell can be seen as our galaxy approaches the Andromeda Galaxy as both shells meet and form this blue glow.
When a charged partical leaves its galaxy, it is stripped of its charge and made neutral, no longer effected by gravity.
FACT-1: Dark matter and charged Hydrogen helium make 84% of everything each, and both under the influence of gravity.
FACT-2: Dark energy and neuteal hydrogen and helium makes up 4% of everything,and do t interact with gravity.
The galaxy will pull it self together as the space outside expand?
So let's remove the dark stuff and add or take away charge. Get it..
There is no dark matter, and if there were, you would be made mostley of it, not hydrogen, helium and Electrolights.