Discovery of the Musket Ball Cluster, a System of Colliding Galaxy Clusters
ScienceDaily (Apr. 12, 2012) — The newly discovered galaxy cluster is called DLSCL J0916.2+2951. It is similar to the Bullet Cluster, the first system in which the separation of dark and normal matter was observed, but with some important differences. The newly discovered system has been nicknamed the “Musket Ball Cluster” because the cluster collision is older and slower than the Bullet Cluster.
Finding another system that is further along in its evolution than the Bullet Cluster gives scientists valuable insight into a different phase of how galaxy clusters — the largest known objects held together by gravity — grow and change after major collisions. Researchers used observations from NASA’s Chandra X-ray Observatory and Hubble Space Telescope as well as the Keck, Subaru and Kitt Peak Mayall telescopes to show that hot, X-ray bright gas in the Musket Ball Cluster has been clearly separated from dark matter and galaxies.
Image Info: This image shows the Musket Ball Cluster at about 700 million years post-collision, showing it is much older than the Bullet Cluster. It is about 5.2 billion light years from Earth. X-rays are red-purple, visible galaxies appear orange and white, mass map in blue.
Image Credit: X-ray: NASA/CXC/UCDavis/W.Dawson et al; Optical: NASA/STScI/UCDavis/W.Dawson et al.