Galaxy collision separates dark matter from regular matter

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SUMMARY

The recent discussion highlights the phenomenon of dark matter separating from normal matter during galaxy collisions, specifically referencing the Bullet Cluster as a key example. The collision causes normal matter to decelerate due to electromagnetic interactions, while dark matter continues to move forward, leading to a decoupling effect. This observation provides strong evidence supporting dark matter theory, although alternative theories like Modified Newtonian Dynamics (MOND) also attempt to explain these phenomena through different gravitational interactions.

PREREQUISITES
  • Understanding of dark matter and its properties
  • Familiarity with galaxy collision dynamics
  • Knowledge of Modified Newtonian Dynamics (MOND)
  • Basic concepts of gravitational lensing
NEXT STEPS
  • Research the Bullet Cluster and its implications for dark matter theory
  • Explore the mathematics behind Modified Newtonian Dynamics (MOND)
  • Investigate gravitational lensing and its role in astrophysics
  • Study the effects of galaxy collisions on matter distribution
USEFUL FOR

Astronomers, astrophysicists, and students of cosmology interested in the interactions between dark and normal matter during cosmic events.

DaveC426913
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TL;DR
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?
 
Astronomy news on Phys.org
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.
 
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.
 

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