We study the impact of cluster environment on the morphology of a sample of 4304 extended radio galaxies from Radio Galaxy Zoo. A total of 87% of the sample lies within a projected 15 Mpc of an optically identified cluster. Brightest cluster galaxies (BCGs) are more likely than other cluster members to be radio sources, and are also moderately bent. The surface density as a function of separation from cluster center of non-BCG radio galaxies follows a power law with index -1.10 ±0.03 out to 10 r 500 (∼7 Mpc), which is steeper than the corresponding distribution for optically selected galaxies. Non-BCG radio galaxies are statistically more bent the closer they are to the cluster center. Within the inner 1.5 r 500 (∼1 Mpc) of a cluster, non-BCG radio galaxies are statistically more bent in high-mass clusters than in low-mass clusters. Together, we find that non-BCG sources are statistically more bent in environments that exert greater ram pressure. We use the orientation of bent radio galaxies as an indicator of galaxy orbits and find that they are preferentially in radial orbits. Away from clusters, there is a large population of bent radio galaxies, limiting their use as cluster locators; however, they are still located within statistically overdense regions. We investigate the asymmetry in the tail length of sources that have their tails aligned along the radius vector from the cluster center, and find that the length of the inward-pointing tail is weakly suppressed for sources close to the center of the cluster.
Bibliographical noteFunding Information:
Partial support for this work for A.F.G., L.R., and T.W.J. comes from National Science Foundation grant AST-171405 to the University of Minnesota. The support for J.-A.K. comes from the National Research Foundation of Korea to the Center for Galaxy Evolution Research through grant program No. 2017R1A5A1070354. H.A. benefited from University of Guanajuato grant DAIP #66/2018. F.dG. is supported by the VENI research program with project number 639.041.542, which is financed by the Netherlands Organisation for Scientific Research (NWO). S.S.S. thanks the Australian Research Council for an Early Career Fellowship, DE130101399.
This publication makes use of radio data from the Karl G. Jansky Very Large Array, operated by the National Radio Astronomy Observatory. The NRAO is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for High-Performance Computing at the University of Utah. The SDSS website iswww.sdss.org. This research made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013, 2018), and packages in the SciPy ecosystem (Jones et al. 2001).
- galaxies: clusters: intracluster medium
- radio continuum: galaxies