Where the Wild Things Are: Galaxy Evolution and Radio Source Properties in the High-z COBRA Survey

Building a map of galaxy cluster evolution requires clusters spanning a range of redshifts, masses, and dynamical and evolutionary states. One way to build this sample is with radio AGNs, which have long been used to trace clusters at higher redshift. Specifically, bent, double-lobed radio sources are an effective tracer of clusters. Bent radio sources have a characteristic "C" shape, which is created when ram pressure from a dense gaseous medium, like the ICM, bends the radio lobes. Using the high-z Clusters Occupied by Bent Radio AGN (COBRA) survey, we identify a large sample of high-z cluster/protocluster candidates hosting bent AGNs. Using optical and IR images, we find strong red sequence populations in 39 cluster candidates at 0.35 < z < 2.2. In these clusters, we probe the red sequence to determine if BCGs preferentially host high-z bent AGNs. By correlating the distribution of red sequence galaxies in each cluster with the bending angle, we find that richer clusters host narrower bent AGNs. If ICM density scales with richness, the appearance of narrower bent AGNs may indicate which clusters have a denser or earlier forming ICM. Lastly, using VLA FIRST, VLASS, and LOFAR observations, we measure spectral indices for our high-z bent AGNs to further determine what causes the morphology of these bent radio sources and tease potential differences in the ICM distribution in our clusters.