2006/10/31 by V. Smolčić, V. Smolcic, E. Schinnerer +20
Physics and Astronomy · #Abell 2744 #Astronomy and Astrophysical Research #Brightest cluster galaxy #Cluster (spacecraft) #Coma Cluster #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Intracluster medium #Radio Astronomy Observations and Technology #Radio galaxy #Ram pressure #astro-ph
paper · pdf · doi:10.1086/516583
18 pages, 13 figures; accepted for publication in ApJS, COSMOS special issue; added color figure (Fig. 13) which was previously unavailable
arxiv created 2006/11/17 · openalex publication_date 2007/08/31 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We have identified a complex galaxy cluster system in the COSMOS field via a wide-angle tail (WAT) radio galaxy, consistent with the idea that WAT galaxies can be used as tracers of clusters. The WAT galaxy, CWAT-01, is coincident with an elliptical galaxy resolved in the HST ACS image. Using the COSMOS multiwavelength data set, we derive the radio properties of CWAT-01 and use the optical and X-ray data to investigate its host environment. The cluster hosting CWAT-01 is part of a larger assembly consisting of a minimum of four X-ray luminous clusters within ~2 Mpc distance. We apply hydrodynamic models that combine ram pressure and buoyancy forces on CWAT-01. These models explain the shape of the radio jets only if the galaxy's velocity relative to the intracluster medium (ICM) is in the range of about 300-550 km s^(-1), which is higher than expected for brightest cluster galaxies (BCGs) in relaxed systems. This indicates that the CWAT-01 host cluster is not relaxed but is possibly dynamically young. We argue that such a velocity could have been induced through subcluster merger within the CWAT-01 parent cluster and/or cluster-cluster interactions. Our results strongly indicate that we are witnessing the formation of a large cluster from an assembly of multiple clusters, consistent with the hierarchical scenario of structure formation. We estimate the total mass of the final cluster to be approximately 20% of the mass of the Coma Cluster.