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The Impact of CN Line Profile Measurements on the Cosmic Microwave Background Temperature

Published online by Cambridge University Press:  08 February 2017

M. E. Kaiser  and
E. L. Wright
M. E. Kaiser
Affiliation:
University of California, Los Angeles Los Angeles, California USA
E. L. Wright
Affiliation:
University of California, Los Angeles Los Angeles, California USA

Abstract

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We present moderate to high signal-to-noise high-resolution (R ≈ 150,000–170,000) optical spectra toward ζ Oph. Gaussian fits to our data indicate a value of the line-width parameter b, of b = 1.4 ± 0.2 km s−1, along this line of sight. When CN is used as an indirect probe of the cosmic microwave background (CMB) temperature, the line profile is used to determine saturation corrections in the line. This affects column density calculations, which are reflected in the excitation temperature. Current measurements of the b-value along this line of sight range from 0.88 ± 0.02 km s−1 (Crane et al. 1986) to 1.3 ± 0.1 km s−1 (Hegyi, Traub, and Carleton 1972). The extreme range of these b-values yield saturation corrections to the CMB temperature that differ by 0.05 K, which is equal to the quoted precision of current measurements. Preliminary analysis of observations toward HD 29647 indicate that TCMB = 2.70 ± 0.14 K at 2.64 mm toward this line of sight.

Type
IV. Extragalactic Background Radiation and Cosmology
Information
Symposium - International Astronomical Union , Volume 139: The Galactic and Extragalactic Background Radiation , 1990 , pp. 390 - 391
Copyright
Copyright © Kluwer 1990 

References

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