1999/04/29 by Joanne C. Baker, J. C. Baker, Keith Grainge +14 · 1 citation
Physics and Astronomy · #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #Radio Astronomy Observations and Technology #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.1999.02829.x
5 pages, 5 figures (gif), submitted to MNRAS
arxiv created 1999/04/29 · openalex publication_date 1999/10/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We describe observations at frequencies near 15 GHz of the second 2×2 deg2 field imaged with the Cambridge Cosmic Anisotropy Telescope (CAT). After the removal of discrete radio sources, structure is detected in the images on characteristic scales of about half a degree, corresponding to spherical harmonic multipoles in the range ℓ≈330–680. A Bayesian analysis confirms that the signal arises predominantly from the cosmic microwave background (CMB) radiation for multipoles in the lower half of this range; the average broad-band power in a bin with centroid ℓ = 422 (θ≈51 arcmin) is estimated to be . For multipoles centred on ℓ=615 (θ≈35 arcmin), we find contamination from Galactic emission is significant, and constrain the CMB contribution to the measured power in this bin to be ΔTT<2.0×10−5 (1σ upper limit). These new results are consistent with the first detection made by CAT in a completely different area of sky. Together with data from other experiments, this new CAT detection adds weight to earlier evidence from CAT for a downturn in the CMB power spectrum on scales smaller than 1 deg. Improved limits on the values of H0 and Ω are determined using the new CAT data.