NOAO >   Observing Info >   Approved Programs >   2001A-0069

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Proposal Information for 2001A-0069


PI: Marc Postman, STScI, postman@stsci.edu
Address: 3700 San Martin Drive, Baltimore, MD 21218

CoI: Tod R. Lauer, NOAO
CoI: William Oegerle, JHU

Title: Clustering of Galaxy Clusters at Intermediate Redshifts

Abstract: We propose to continue a redshift survey of 141 objectively selected galaxy clusters to measure their clustering properties and constrain models of the formation of structure in the universe. This is the first redshift survey to probe cluster correlations on comoving scales of ~ 50h_75^-1 Mpc at z ~ 0.5 and will thus provide an original and important constraint on the evolution of large-scale structure. The cluster sample comes from our deep (I_\rm AB \le 24), contiguous 16 deg^2 I-band KPNO 4-m survey. The proposed observations distinguish themselves from other ongoing distant cluster redshift work in that this survey will be able to provide meaningful constraints on the \it large-scale spatial distribution of moderate redshift clusters owing to the large angular area and contiguous geometry of the parent survey. The availability of the HET/LRS provides a highly efficient solution to the acquisition of redshifts for the 80 cluster candidates with 0.6 \le z_est \le 0.7. The systems with z_est > 0.6 are needed to assure complete sampling of the cluster population at z_obs ~ 0.5. The survey declination (52+/-2^\circ) and observational strategy are extremely well-suited to the initial capabilities and queue observing mode of the HET. The 4m/RCSP is well suited to completing the survey of the z_est < 0.6 systems. Interim projects which are being executed during the course of the survey include homogeneous studies of intermediate z brightest cluster galaxies, the space densities of clusters and superclusters, and cross-correlations with existing VLA 20 cm data. This survey began using the KPNO 4m to obtain redshifts for the 0.3 \le z_est < 0.6 sample. So far, we have observed 31 clusters and we're presently ~25% complete with the z_est < 0.6 observations (75% complete for z_est < 0.4). We have discovered at least 2 superclusters at z=0.23 and z=0.50.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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