2006/02/28 by Kyle Dawson, K. S. Dawson, W. L. Holzapfel +4 · 1 citation
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #Radio Astronomy Observations and Technology #astro-ph
paper · pdf · doi:10.1086/505172
published as Astrophys.J.647:13-24,2006 · Accepted by ApJ, 17 pages
arxiv created 2006/04/14 · openalex publication_date 2006/08/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We report the final results of our study of the cosmic microwave background (CMB) with the BIMA array. Over 1000 hr of observation were dedicated to this project exploring CMB anisotropy, on scales between 1' and 2' in eighteen 6 6 FWHM fields. In the analysis of the CMB power spectrum, the visibility data are divided into two bins, corresponding to different angular scales. Modeling the observed excess power as a flat band of average multipole l eff = 5237, we find Δ T = 220 μK 2 at 68% confidence and Δ T > 0 μK 2 with 94.7% confidence. In a second band, with average multipole of l eff = 8748, we find Δ T consistent with zero and an upper limit of 880 μK 2 at 95% confidence. An extensive series of tests and supplemental observations with the VLA provide strong evidence against systematic errors or radio point sources being the source of the observed excess power. The dominant source of anisotropy on these scales is expected to be the Sunyaev-Zel'dovich (SZ) effect in a population of distant galaxy clusters. If the excess power is due to the SZ effect, we can place constraints on the normalization of the matter power spectrum σ 8 = 1.03 at 68% confidence. The distribution of pixel fluxes in the BIMA images is found to be consistent with simulated observations of the expected SZ background and rules out instrumental noise or radio sources as the source of the observed excess power, with confidence similar to the detection of excess power. Follow-up optical observations to search for galaxy overdensities anticorrelated with flux in the BIMA images, as might be expected from the SZ effect, proved to be inconclusive.