The High-Redshift Clusters Occupied by Bent Radio AGN (COBRA) Survey: Radio Source Properties

• Main Authors: Golden-Marx, Emmet, Blanton, Elizabeth, Rachel-Paterno-Mahler, Brodwin, Mark, Ashby, Matt, Moravec, Emily, Shen, Lu, Lemaux, Brian, Lubin, Lori, Gal, Roy, Tomczak, Adam
• Format: Journal Article
• Language: English
• Published: 24-11-2020
• Subjects: Physics - Astrophysics of Galaxies
• DOI: 10.48550/arxiv.2011.12313

The shape of bent, double-lobed radio sources requires a dense gaseous
medium. Bent sources can therefore be used to identify galaxy clusters and
characterize their evolutionary history. By combining radio observations from
the Very Large Array Faint Images of the Radio Sky at Twenty centimeters (VLA
FIRST) survey with optical and infrared imaging of 36 red sequence selected
cluster candidates from the high-z Clusters Occupied by Bent Radio AGN (COBRA)
survey (0.35 < z < 2.2), we find that radio sources with narrower opening
angles reside in richer clusters, indicating that the cluster environment
impacts radio morphology. Within these clusters, we determine 55.5% of our
radio host galaxies are brightest cluster galaxies (BCGs) and that the
remainder are associated with other luminous galaxies. The projected
separations between the radio sources and cluster centers and the sizes of the
opening angles of bent sources follow similar distributions for BCG and non-BCG
host populations, suggesting that COBRA host galaxies are either BCGs or
galaxies that may evolve into BCGs. By measuring the orientation of the radio
sources relative to the cluster centers, we find between 30% and 42% of COBRA
bent sources are outgoing and have passed through the cluster center, while
between 8% and 58% of COBRA bent sources are infalling. Although these sources
typically do not follow directly radial paths, the large population of outgoing
sources contrasts what is observed in low-z samples of bent sources and may
indicate that the intracluster medium is less dense in these high-z clusters.