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|Title:||Brightest cluster galaxies in the extended GMRT radio halo cluster sample. Radio properties and cluster dynamics||Authors:||Kale, R.
|Issue Date:||2015||Journal:||ASTRONOMY & ASTROPHYSICS||Number:||581||First Page:||A23||Abstract:||Aims: First-ranked galaxies in clusters, usually referred to as brightest cluster galaxies (BCGs), show exceptional properties over the whole electromagnetic spectrum. They are the most massive elliptical galaxies and show the highest probability to be radio loud. Moreover, their special location at the centres of galaxy clusters raises the question of the role of the environment in shaping their radio properties. In the attempt to separate the effect of the galaxy mass and of the environment on their statistical radio properties, we investigate the possible dependence of the occurrence of radio loudness and of the fractional radio luminosity function on the dynamical state of the hosting cluster. <BR /> Methods: We studied the radio properties of the BCGs in the Extended GMRT Radio Halo Survey (EGRHS), which consists of 65 clusters in the redshift range 0.2-0.4, with X-ray luminosity L<SUB>X</SUB> ≥ 5 × 10<SUP>44</SUP> erg s<SUP>-1</SUP>, and quantitative information on their dynamical state from high-quality Chandra imaging. We obtained a statistical sample of 59 BCGs, which we divided into two classes, depending on whether the dynamical state of the host cluster was merging (M) or relaxed (R). <BR /> Results: Of the 59 BCGs, 28 are radio loud and 31 are radio quiet. The radio-loud sources are favourably located in relaxed clusters (71%), while the reverse is true for the radio-quiet BCGs, which are mostly located in merging systems (81%). The fractional radio luminosity function for the BCGs in merging and relaxed clusters is different, and it is considerably higher for BCGs in relaxed clusters, where the total fraction of radio loudness reaches almost 90%, to be compared to the ~30% in merging clusters. For relaxed clusters, we found a positive correlation between the radio power of the BCGs and the strength of the cool core, consistent with previous studies on local samples. <BR /> Conclusions: Our study suggests that the radio loudness of the BCGs strongly depends on the cluster dynamics; their fraction is considerably higher in relaxed clusters. We compare our results with similar investigations and briefly discuss them in the framework of AGN feedback.||Acknowledgments:||We thank R. Fanti for the many insightful discussions. Thanks are due to S. Ettori for providing the routines we used for the X-ray data analysis and for the derivation of the cluster morphological parameters. R.K. and T.V. acknowledge partial support by PRIN-INAF 2008 and by FP7-People-2009 IRSES CAFEGroups project under grant agreement 247653. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the US Department of Energy Office of Science. The SDSS-III web site is http://www.sdss3.org/ . SDSS-III is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS-III Collaboration including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, Carnegie Mellon University, University of Florida, the French Participation Group, the German Participation Group, Harvard University, the Instituto de Astrofisica de Canarias, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, Max Planck Institute for Extraterrestrial Physics, New Mexico State University, New York University, Ohio State University, Pennsylvania State University, University of Portsmouth, Princeton University, the Spanish Participation Group, University of Tokyo, University of Utah, Vanderbilt University, University of Virginia, University of Washington, and Yale University. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.||URI:||http://hdl.handle.net/20.500.12386/30381||URL:||https://www.aanda.org/articles/aa/full_html/2015/09/aa26341-15/aa26341-15.html||ISSN:||0004-6361||DOI:||10.1051/0004-6361/201526341||Bibcode ADS:||2015A&A...581A..23K||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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