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Mapping the Galactic Free-Free Foreground via Interstellar Hα Emission

Published online by Cambridge University Press:  26 May 2016

R. J. Reynolds
Affiliation:
Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706, USA
L. M. Haffner
Affiliation:
Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706, USA

Abstract

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Recently completed Hα surveys of large portions of the sky can be used to create maps of the free-free intensity distribution at high Galactic latitude that are independent of the spectral fits to the CMB data. This provides an opportunity to test the accuracy of the spectral fitting procedures and to search for other sources of Galactic forground contamination that could be confused spectrally with the free-free, such as spinning dust grains. The Wisconsin Hα Mapper (WHAM) survey has sampled the sky north of declination −30° at about one degree angular resolution and has revealed that, except for a few isolated regions of enhanced emission, δTff (30 GHz) ≲ 30 μK at Galactic latitudes near 15°, decreasing to δTff(30 GHz) ≲ 4 μK at latitudes above 50°. Also in progress are Hα surveys that sample the sky at higher angular resolution.

Type
Part IV: Interpreting CMB Observations
Copyright
Copyright © Astronomical Society of the Pacific 2005 

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