Open AccessDetection of cosmic microwave background structure in a second field with the Cosmic Anisotropy Telescope
Author(s) -
Baker Joanne C.,
Grainge Keith,
Hobson M. P.,
Jones Michael E.,
Kneissl R.,
Lasenby A. N.,
O’Sullivan C. M. M.,
Pooley Guy,
Rocha G.,
Saunders Richard,
Scott P. F.,
Waldram E. M.
Publication year - 1999
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1999.02829.x
Subject(s) - physics , cosmic microwave background , astrophysics , anisotropy , telescope , sky , cosmic background radiation , spectral density , cosmic cancer database , background radiation , astronomy , south pole telescope , radiation , optics , statistics , mathematics
We describe observations at frequencies near 15 GHz of the second 2×2 deg 2 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 =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 Δ T T <2.0×10 −5 (1 σ 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 H 0 and Ω are determined using the new CAT data.