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,^[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]

Musket Ball Cluster
Observation data (Epoch J2000.0[1])
Constellation(s)	Cancer
Right ascension	09h 16m 10.9s[1]
Declination	+29° 48′ 44″[1]
Redshift	0.53[2]
Other designations
Musket Ball Cluster,[3] DLSCL J0916.2+2951,[2] SHELS J0916.2+2949[1]

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]

See also

• Bullet Group

Other dissociative galaxy cluster mergers known at the time of discovery

• Bullet Cluster (2006)
• MACS J0025.4-1222 (2008)
• Abell 520 (2007)
• Abell 2744 (2011)
• Abell 2163 (2011)
• Abell 1759 (2011)