The Bullet Cluster!!! One of the most famous galaxy clusters. Contains plenty of DARK MATTER!
We all know what matter is: solid, liquid, gas…plasma aka some type of material that emits or reflects light so we can see it. However dark matter is exactly what the name is-DARK.
It doesn’t emit or reflect light, so how do we detect it?? By observing the motion of stars and gas!!
Astronomer Zwicky noticed that the movement of matter in the Coma galaxy cluster shouldn’t have moved as it did unless it contained A LOT more mass than visible.
The Bullet Cluster is fascinating because it is TWO massive clumps of galaxy clusters, clustered together!!!!! (that’s a lot of clustering).
As a result from the collision a shock wave in the plasma happened and gave the cluster it’s name.
This plasma was located between the two galaxy clusters, leaving open the mystery of the mass detected around the clusters. This being it’s own independent measurement lead astronomers to conclude on dark matter filling up this visibly “empty space.”
Composite image of X-ray (pink) and weak gravitational lensing (blue).
X-ray: NASA/CXC/CfA/ M.Markevitch et al.; Lensing Map: NASA/STScI; ESO WFI; Magellan/U.Arizona/ D.Clowe et al. Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al.
Image and info from: arstecnica.com