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Recent Measurements of the Cosmic Microwave Radiation

Published online by Cambridge University Press:  03 August 2017

David T. Wilkinson
David T. Wilkinson*
Affiliation:
Joseph Henry Laboratories, Princeton University, P. O. Box 708, Princeton, N J 08544 USA

Abstract

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Recent measurements of the spectrum and anisotropy of the cosmic microwave may be showing deviations from a perfectly homogeneous blackbody flux. Improved spectral measurements at wavelengths of 3 cm and 1.2 cm disagree weakly; and new results from a rocket show large excess flux at wavelengths of 0.71 and 0.48 mm. The same instrument measured a radiation temperature at λ = 1.16 mm of 2.795 ± 0.018 K in good agreement with results at longer wavelengths. The observed excess flux at short wavelengths may be due to: local contaminants; dust emission from active galaxies at high redshift; or inverse Compton scattering of microwave photons from hot electrons at large redshift (Sunyaev-Zel'dovich effect). Anisotropy of ΔT/T = 3.7 × 10−5 has been reported on an angular scale of 8° at a wavelength of 3 cm. Measurements on a similar angular scale at λ = 6 cm (reported at this meeting) do not show the anisotropy at the flux level expected if Galactic emission were the source of the anisotropy at λ = 3 cm. The standard model has not yet predicted anisotropy this large at 8°, but without doubt it soon will. Long integrations with the Very Large Array at λ = 6 cm are showing resolved structures on angular scales of 15 to 30 arcseconds. Observations at another wavelength are needed to see if these are radio sources at high redshift or perturbations in the 2.77 K radiatoin.

Type
Research Article
Information
Symposium - International Astronomical Union , Volume 130: Large Scale Structures of the Universe , 1988 , pp. 7 - 14
Copyright
Copyright © Reidel 1988 

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