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Published April 10, 2010 | Published
Journal Article Open

Identifying Dynamically Young Galaxy Groups Via Wide-angle Tail Galaxies: A Case Study in the COSMOS Field at z = 0.53


We present an analysis of a wide-angle tail (WAT) radio galaxy located in a galaxy group in the COSMOS field at a redshift of z = 0.53 (hereafter CWAT-02). We find that the host galaxy of CWAT-02 is the brightest galaxy in the group although it does not coincide with the center of mass of the system. Estimating (1) the velocity of CWAT-02, relative to the intra-cluster medium, and (2) the line-of-sight peculiar velocity of CWAT-02's host galaxy, relative to the average velocity of the group, we find that both values are higher than those expected for a dominant galaxy in a relaxed system. This suggests that CWAT-02's host group is dynamically young and likely in the process of an ongoing group merger. Our results are consistent with previous findings showing that the presence of a WAT galaxy in a galaxy group or cluster can be used as an indicator of dynamically young non-relaxed systems. Taking the unrelaxed state of CWAT-02's host group into account, we discuss the impact of radio-active galactic nucleus (AGN) heating from CWAT-02 onto its environment, in the context of the missing baryon problem in galaxy groups. Our analysis strengthens recent results suggesting that radio-AGN heating may be powerful enough to expel baryons from galaxy groups.

Additional Information

© 2010 American Astronomical Society. Received 2009 November 6; accepted 2010 February 23; published 2010 March 23. A.O. thanks California Institute of Technology for generous support through NASA grants 1292462 and 1344606. V.S. acknowledges support from the Owens Valley Radio Observatory, which is supported by the National Science Foundation through grant AST-0838260. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement 229517. V.S. and A.O. thank Unity through Knowledge Fund (www.ukf.hr) for collaboration support through the "Homeland Visit" grant. S.G. acknowledges support by the DFG Cluster of Excellence "Origin and Structure of the Universe" (www.universe-cluster.de). C.C. acknowledges support from the Max-Planck Society and the Alexander von Humboldt Foundation through the Max-Planck-Forschungspreis 2005. G.Z. acknowledges support from an INAF contract PRIN-2007/ and an ASI grant ASI/COFIS/WP3110 I/026/ 07/0.

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Published - Oklopcic2010p7477Astrophys_J.pdf


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