Musket Ball Cluster

The Musket Ball Cluster (DLSCL J0916.2+2951) is a galaxy cluster that exhibits separation between its baryonic matter and dark matter components. The cluster is a recent merger of two galaxy clusters. It is named after the Bullet Cluster, as it is a slower collision, and older than the Bullet Cluster. This cluster is further along the process of merger than the Bullet Cluster, being some 500 million years older, at 700 million years old. The cluster was discovered in 2011 by the Deep Lens Survey. As of 2012, it is one of the few galaxy clusters to show separation between its dark matter and baryonic matter components.

Characteristics
As of 2012, it is one of seven galaxy clusters that exhibit separation of dark matter and baryonic matter following cluster collision and merger. The separation between the galaxies and their dark matter components is on average 19000 ly. This separation may indicate that dark matter may interact with itself, through a dark force (a force that only interacts with dark matter) or a set of dark forces. The galaxy cluster itself is some 8 e6ly across.