Galaxy clusters are the largest gravitationally-bound systems in the universe. Although there are many known spectroscopically confirmed low-redshift clusters, few high-redshift clusters have been found. To probe the earliest eras of cluster formation and better understand galaxy cluster evolution, observations of high-z clusters with a variety of morphological states and masses are needed. One known tracer of high-z clusters is radio loud active galactic nuclei (RLAGN). Particularly, bent, double-lobed radio sources are an excellent tracer of galaxy clusters. These bent radio AGN have a distinct "c" shape indicative of ram pressure caused by a gaseous medium; specifically, the AGN lobes are bent due to the relative motion of the host galaxy with respect to the intracluster medium. I will present results from the Clusters Occupied by Bent Radio AGN (COBRA) Survey, which consists of 646 bent, double-lobed radio sources from the VLA FIRST Survey and has observations in the infrared from Spitzer and optical from the 4.3m Discovery Channel Telescope. The COBRA survey spans the redshift range 0.5 < z < 3.0 and includes candidates with a wide range of masses and dynamical states. Using IR and optical data, we have measured galaxy overdensities, located red sequence galaxies, and determined photometric redshifts. As bent radio AGN are not necessarily found in brightest cluster galaxies, we used local galaxy surface density measurements to analyze the spatial offset between our bent radio AGN and newly-determined cluster centers, which are estimated using the overdensity of red galaxies. We also use these new centers to better identify cluster candidates and probe the infall angle of our target AGN within the cluster. We measured the surface density of all galaxies and red galaxies to better trace large-scale cluster morphologies and dynamical states to determine if our bent radio AGN are found in merging or relaxed galaxy clusters. We have found that at least 30% of our high-z bent radio sources are in cluster environments and that these cluster environments appear to be in a variety of morphological states.
American Astronomical Society Meeting Abstracts #233
- Pub Date:
- January 2019