Newly discovered Musket Ball cluster 'may hold clues about dark matter'

Washington, Apr 13 (ANI): Astronomers have discovered a system of colliding galaxy clusters, nicknamed the "Musket Ball" cluster.

It is called so because it is an older and slower cousin to the famous Bullet Cluster, where "normal" and dark matter have been torn apart.

Finding this cluster gives scientists insight into a different phase of how galaxy clusters grow and change after major collisions.

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.

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.

In addition to the Bullet Cluster, five other similar examples of merging clusters with separation between normal and dark matter and varying levels of complexity, have previously been found. In these six systems, the collision is estimated to have occurred between 170 million and 250 million years earlier.

In the Musket Ball Cluster, the system is observed about 700 million years after the collision. Taking into account the uncertainties in the age estimate, the merger that has formed the Musket Ball Cluster is two to five times further along than in previously observed systems.

Also, the relative speed of the two clusters that collided to form the Musket Ball cluster was lower than most of the other Bullet Cluster-like objects.

The special environment of galaxy clusters, including the effects of frequent collisions with other clusters or groups of galaxies and the presence of large amounts of hot, intergalactic gas, is likely to play an important role in the evolution of their member galaxies.

However, it is still unclear whether cluster mergers trigger star formation, suppress it, or have little immediate effect. The Musket Ball Cluster holds promise for deciding between these alternatives.

The Musket Ball Cluster is located about 5.2 billion light years away from Earth.

The study has been published in The Astrophysical Journal Letters. (ANI)