NOAO >   Observing Info >   Approved Programs >   2009B-0355

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Proposal Information for 2009B-0355


PI: Felipe Menanteau, Rutgers University, felipe@physics.rutgers.edu
Address: Physics Department, 136 Frelinghuysen Rd, Piscataway, NJ 08854, USA

CoI: John P. Hughes, Rutgers University
CoI: Leopoldo Infante, P. Univ. Catolica de Chile
CoI: Jean-Baptiste Juin, P. Univ. Catolica de Chile
CoI: Felipe Barrientos, P. Univ. Catolica de Chile
CoI: Toby Marriage, Princeton University
CoI: Matt Hilton, University of KwaZulu-Natal, South Africa
CoI: Ryan Warne, University of KwaZulu-Natal, South Africa
CoI: Kavilan Moodley, University of KwaZulu-Natal, South Africa

Title: Testing the Selection Function of Galaxy Clusters in the New SZE Surveys

Abstract: We propose a critical test of the Sunyaev-Zel'dovich Effect (SZE) selection function for galaxy clusters. Our study uses maps of the Cosmic Microwave Background Radiation acquired by the Atacama Cosmology Telescope (ACT) during 5 months of observing in 2008 over some 400 deg^2 of the southern sky. Several well-known, massive clusters including the famous ``Bullet Cluster'' were detected as 145-GHz SZE decrements in this survey. The goal of this proposal is to obtain optical imaging data on ~100 unidentified 145-GHz decrements using the SOAR Optical Imager (SOI) in order to determine the recovery fraction of true massive clusters based on confirming the presence of a brightest cluster galaxy (BCG) and red sequence of accompanying cluster members. The depth of the individual observations in gri has been set so that we can detect faint red-sequence galaxies (0.4L^*) at a redshift of 0.8. Over 90% of ACT SZE clusters are expected to lie at redshifts between 0 and 0.8. Two colors will ensure detectability of the red sequence across this full redshift range. The fraction of true clusters associated with SZE decrements is a fundamental number that must be determined before cosmology with SZE clusters can begin.


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