Distant clusters of galaxies are important probes of cosmology and are key players in unraveling the mysteries behind galaxy formation and evolution and the development of large scale structure in the Universe. Any clusters that are confirmed at very great distances add significantly to the few that are known. This project employs a unique method for identifying new, distant clusters of galaxies, and this sample of distant galaxy clusters will help in determining the epoch of galaxy formation, in studying the galaxy populations of clusters over time, and in constraining cosmological models including dark energy.
Clusters usually contain bright elliptical galaxies near their centers, and these galaxies host supermassive black holes in their cores. Accreting supermassive black holes produce jets and lobes detected in the radio, and these jets and lobes become distorted as they interact with the surrounding intracluster medium (ICM). These distortions sometimes result in the lobes being bent in the same direction, resulting in a wide-angle tail (WAT) morphology. Significant groundwork has been laid in studying the cluster environments of WATs at low-to-moderate redshifts. In addition, a large sample of 653 WATs with cluster environments too faint (and therefore distant) to be studied with the Sloan Digital Sky Survey has been assembled. All of these objects are being observed in the infrared with Spitzer. Based on cluster association rates at lower redshift z, this project's sample is expected to reveal approximately 400 new clusters at z > 0.7. Follow-up deep optical imaging is the next step in the survey and will be achieved using the 4.3-meter Discovery Channel Telescope (DCT). By the nature of their selection, all the clusters will contain radio-loud active galaxies, allowing the study of active-galactic nucleus (AGN) feedback at high redshift. Poor, low-mass clusters at high redshifts are particularly important for studying AGN feedback and for constraining models of the Sunyaev-Zel'dovich power spectrum. High-redshift, low-mass clusters are also the most difficult ones to find using other cluster survey techniques, making this survey particularly useful because it will locate distant clusters with a wide range of masses.
Research results of this project will be included in undergraduate classes. Students at both the undergraduate and graduate levels will be involved with all aspects of the project. The Principal Investigator (PI) will mentor undergraduate and graduate students, who will accompany the PI on observing trips to the telescope. The PI will engage the community through public elementary school visits and collaboration on science museum exhibits. Students and the PI will participate with public outreach efforts with the Discovery Channel, including films and online science reporting.
