A Search for Galaxy Clusters Using the Sunyaev-Zel’dovich Effect

• Main Author: Runyan, Marcus Christian
• Format: Thesis
• Language: English
• Published: 2003
• Subjects: Lambda; South Pole; South pole
• Online Access: https://thesis.library.caltech.edu/2228/; https://thesis.library.caltech.edu/2228/1/mcr_thesis.pdf; https://resolver.caltech.edu/CaltechETD:etd-05292003-125239

This thesis describes the instrumental design and observations with the Arcminute Cosmology Bolometer Array Receiver (ACBAR). We have used ACBAR to make very sensitive, high resolution maps of the Cosmic Microwave Background (CMB) and have searched within these maps for previously unknown massive clusters of galaxies through the Sunyaev-Zel'dovich effect. ACBAR is a 16-pixel, millimeter-wave, 240 mK bolometer array that is configurable to observe simultaneously at 150, 220, 280, and 350 GHz. The receiver observes from the 2m Viper telescope at the South Pole from which it has beam sizes of ~4-5' at all frequencies. We have taken advantage of improvements in bolometric detector technology and the superb observing conditions at the South Pole to image the microwave sky at multiple millimeter wavelengths. Here we present the results of observing ~20 deg^2 for 16 weeks in 2002. These represent the deepest CMB observations to date with a sensitivity of ~5 muK per 5' beam at 150 GHz in the deepest part of the map. We present the results from 150 GHz and employ an optimal filter to remove the primary CMB. We detect no clusters above 4 times the post-filter map RMS in the most sensitive 10 deg^2 of the maps. We perform a Monte Carlo simulation to determine the cluster detection efficiency of the survey using the measured noise covariance and realizations of the CMB. We use the results of the simulation to estimate the expected cluster yield of the survey as a function of cosmological parameters. The non-detection of clusters allows us to place a 2 sigma upper limit upon the variance of the smoothed density field of sigma_8 < 1.10 (Omega_M/0.3)^{-0.23} in a flat Lambda-CDM concordance cosmology.