Baker, Joanne C and Grainge, Keith and Hobson, M. P. and Jones, Michael E. and Kneissl, R. and Lasenby, A. and O'Sullivan, Créidhe and Pooley, Guy and Rocha, G. and Saunders, Richard and Scott, P. F. and Waldram, E. M. (1999) Detection of Cosmic Microwave Background Structure in a Second Field with the Cosmic Anisotropy Telescope. Monthly Notices of the Royal Astronomical Society. pp. 1-10. ISSN 0035-8711

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Abstract

We describe observations at frequencies near 15 GHz of the second 2x2 degree 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 approximate 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 (theta = 51') is estimated to be Delta_T/T=2.1^{+0.4}_{-0.5} x 10^{-5}. For multipoles centred on l=615 (theta =35'), we find contamination from Galactic emission is significant, and constrain the CMB contribution to the measured power in this bin to be Delta_T/T <2.0 x 10^{-5} (1-sigma 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 degree. Improved limits on the values of H_0 and Omega are determined using the new CAT data.

Item Type:	Article
Keywords:	Cosmic microwave background; Cosmology; observations;
Academic Unit:	Faculty of Science and Engineering > Experimental Physics
Item ID:	18851
Depositing User:	Dr. Créidhe O'Sullivan
Date Deposited:	10 Sep 2024 14:44
Journal or Publication Title:	Monthly Notices of the Royal Astronomical Society
Publisher:	Wiley Blackwell
Refereed:	Yes
URI:	Publisher
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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