Clusters of Galaxies and AGN Feedback

Deep X-ray observations with the Chandra X-ray Observatory reveal detailed structure in cluster centers related to outbursts from supermassive black holes. “Feedback” of energy from these active galactic nuclei (AGN) heats the surrounding gas, limiting star formation. This process has important implications for galaxy formation and evolution. On larger scales, a “sloshing” spiral is seen in the image to the left, related to the merger of a smaller cluster or group with the main cluster.

Image: Abell 2052 (X-ray: NASA/CXC/BU/E.Blanton; Optical: ESO/VLT)

Wide Angle Tail Radio Galaxies

Wide-angle tail (WAT) radio galaxies are frequently found in clusters of galaxies. The jets and lobes of radio emission are distorted from the interaction with the dense intracluster medium. This may occur in clusters undergoing large-scale mergers, but may also be possible in clusters experiencing sloshing. 

Image: Abell 1446 (X-ray: NASA/CXC/BU/E. M. Douglass; Radio: VLA)

High-Redshift Clusters of Galaxies

High-redshift clusters of galaxies are important laboratories for studying galaxy formation and evolution. They can also be used to place constraints on cosmological parameters. Since radio galaxies with distorted lobes are often found in clusters, they can be used as signposts for finding new, distant clusters. An example Spitzer infrared image of a distant cluster located using a bent radio source is shown at left.

Image: Distant cluster (Infrared: NASA/JPL/BU/E.Blanton; Radio: VLA)