Galaxy collision separates dark matter from regular matter

[DaveC426913]

TL;DR Summary

Galaxy collision separates dark matter from regular matter. Is this a compelling case for DM over alternate theories?

"... the gas between the galaxies collided, becoming turbulent and superheated. While both dark and normal matter are influenced by gravity, the normal matter also interacts via electromagnetism, which slowed it down during the collision.

Consequently, the dark matter moved ahead, decoupling from the normal matter."

https://www.earth.com/news/dark-mat...normal-matter-after-galaxy-cluster-collision/

This appears to be analogous to the Bullet Cluster.

Has this been verified, and is it strong evidence in favour of the DM theory? Do any other theories such as MOND explain the Bullet Cluster and now this find?

 

[Ibix]

As I understand it, this kind of thing is explicable in some MOND theories by interactions with other semi-nearby galaxies. Because MOND-ian gravity doesn't drop off at $1/r^2$ and because it adds together differently from Newtonian gravity you can get odd areas of surprisingly strong gravity at long ranges. Thus you occasionally get patches of gravitational lensing displaced from any galaxy - surprisingly so if you are intuitively familiar with Newtonian gravity.

I have never studied any of the maths here and am only regurgitating something I read on here... somewhere... so treat with appropriate caution.

 

[ohwilleke]

It is a problem for strict sense Milgromian MOND theories, but there are at least several modified gravity theories for which it is not a problem.