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arXiv · 1003.0675

Identifying dynamically young galaxy groups via wide-angle tail galaxies: A case study in the COSMOS field at z=0.53

A. Oklopcic·V. Smolcic·S. Giodini·G. Zamorani·L. Birzan·E. Schinnerer·C. L. Carilli·A. Finoguenov·S. Lilly·A. Koekemoer·N. Z. Scoville
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Abstract

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 a) the velocity of CWAT-02, relative to the intra-cluster medium (ICM), and b) 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 wide-angle tail 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-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.

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A. Oklopcic, V. Smolcic, S. Giodini, G. Zamorani, L. Birzan, E. Schinnerer, C. L. Carilli, A. Finoguenov, S. Lilly, A. Koekemoer, N. Z. Scoville. 2010-03-02. Identifying dynamically young galaxy groups via wide-angle tail galaxies: A case study in the COSMOS field at z=0.53. https://doi.org/10.1088/0004-637x%2F713%2F1%2F484

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