The Contribution Of Galactic Free-Free Emission to Anisotropies in the Cosmic Microwave Background Found by the Saskatoon Experiment

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1996-02

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IOP PUBLISHING LTD

Abstract

We made a sensitive, wide-field Ha image of the north celestial polar region. Using this image, we constrain the contribution of irregularities in interstellar free-free emission to the degree-scale anisotropies in the cosmic microwave background detected in recent observations at Saskatoon by the Princeton group. The analysis of the Her image mimics the Saskatoon data analysis: the resulting signal is the strength of irregularities sampled with the Saskatoon beam (i.e., degree-scale) along the 85 degrees declination circle. We found no such irregularities that could be attributed to Her emission. The implied upper bound on the rms variation in free-free brightness temperature is less than 4.6 mu K at 27.5 GHz. The observed cosmic microwave background anisotropies are much larger. Therefore, the contribution of irregularities in interstellar free-free emission to the observed anisotropies is negligible.

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Keywords

cosmic microwave background, instrumentation, miscellaneous, ism,, general, radiometer

Citation

John H. Simonetti et al. 1996 ApJ 458 L1 doi:10.1086/309915