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,[3] being some 500 million years older, at 700 million years old.[4] The cluster was discovered in 2011 by the Deep Lens Survey.[2] As of 2012, it is one of the few galaxy clusters to show a separation between its dark matter and baryonic matter components.[5]
Characteristics
As of 2012, it is one of seven galaxy clusters that exhibit a separation of dark matter and baryonic matter following cluster collision and merger.[3] The separation between the galaxies and their dark matter components is on average 19,000 light-years (5,800 pc). 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.[6] The galaxy cluster itself is some 8 million light-years (2.5 Mpc) across.[7]
^ abcDawson, William A.; Wittman, David; Jee, M. James; Gee, Perry; Hughes, John P.; Tyson, J. Anthony; et al. (19 October 2011). "Discovery of a Dissociative Galaxy Cluster Merger with Large Physical Separation". The Astrophysical Journal Letters. 747 (2) (published March 2012): 6. arXiv:1110.4391. Bibcode:2012ApJ...747L..42D. doi:10.1088/2041-8205/747/2/L42. S2CID119244278. L42.