An international team of scientists was able to conduct a comprehensive multi-wave study of one of the MACS J0417.5-1154 galactic mergers. Clusters of galaxies are usually formed as a result of fusion events and grow by accreting subclusters.
These processes allow the study of matter in conditions that are not available in terrestrial laboratories. For example, fusions of galactic clusters allow a better understanding of the physics of shock and cold fronts observed in a diffuse medium inside clusters, the acceleration of cosmic rays, and the interaction properties of dark matter.
With a redshift of 0.44, the MACS J0417.5-1154 cluster (MACS J0417) is a complex confluent galactic cluster, where the dissociative merge class is observed, since one of the substructures is endowed with its own gas. The researchers decided to conduct a large-scale analysis of the MACS J0417 using the Hubble NASA and Subaru space telescope in Hawaii. At the same time, data from the Chandra X-ray observatory, GMRT radio data, and submillimeter information from the 10.4-meter telescope at the California Institute of Technology were connected.
Composite photo of the MACS J0417.5-1154 galactic cluster confluence captured by the SuprimeCam camera on the Subaru telescope
The analysis showed that MACS J0417 is an extremely massive system, represented by the main cluster and sub-cluster. The estimated total mass is 1.38 quadrillion solar, where the main cluster is 1.15 quadrillion solar, and the subcluster is 196 trillion solar masses (6 times less).
The optical photos of MACS J0417 allowed to explore the first brightest galaxy of clusters. It turned out that it demonstrates an interesting filiform substructure, which seems atypical for normal brightest cluster galaxies. Scientists stressed that we are dealing with a dissociative merger, since the main cluster has saved gas. But in the process of merging, the subcluster did break the gas content. The researchers also managed to find a rotating cold front, distant by 831,000 light years from the center of the cluster.