From NASA Chandra: “Discovery of the Musket Ball Cluster “
Using a combination of powerful observatories in space and on the ground, astronomers have observed a violent collision between two galaxy clusters in which so-called normal matter has been wrenched apart from dark matter through a violent collision between two galaxy clusters.
A system of colliding galaxy clusters, nicknamed the “Musket Ball” cluster, has been discovered.
Astronomers call it this because it is an older and slower cousin to the famous Bullet Cluster, where “normal” and dark matter have been torn apart.
This image shows the Musket Ball Cluster at about 700 million years post-collision, showing it is much older than the Bullet Cluster.
Finding this cluster gives scientists insight into a different phase of how galaxy clusters grow and change after major collisions.
In this composite image [above images], the hot gas observed with Chandra is colored red, and the galaxies in the optical image from Hubble appear as mostly white and yellow. The location of the majority of the matter in the cluster (dominated by dark matter) is colored blue. When the red and the blue regions overlap, the result is purple as seen in the image. The matter distribution is determined by using data from Subaru, Hubble and the Mayall telescope that reveal the effects of gravitational lensing, an effect predicted by Einstein where large masses can distort the light from distant objects.
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