ON THE ORIGINS OF THE HIGH-LATITUDE H{alpha} BACKGROUND
- Ritter Astrophysical Research Center, University of Toledo, Toledo, OH 43606 (United States)
- Department of Physics and Astronomy, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)
- Twin Oaks Observatory, Rock Hill, SC 29730 (United States)
- Concordia College, 901 8th St. S, Moorhead, MN 56562 (United States)
- Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia)
The diffuse high-latitude H{alpha} background is widely believed to be predominantly the result of in situ recombination of ionized hydrogen in the warm interstellar medium of the Galaxy. Instead, we show that both a substantial fraction of the diffuse high-latitude H{alpha} intensity in regions dominated by Galactic cirrus dust and much of the variance in the high-latitude H{alpha} background are the result of scattering by interstellar dust of H{alpha} photons originating elsewhere in the Galaxy. We provide an empirical relation, which relates the expected scattered H{alpha} intensity to the IRAS 100 {mu}m diffuse background intensity, applicable to about 81% of the entire sky. The assumption commonly made in reductions of cosmic microwave background observations, namely that the observed all-sky map of diffuse H{alpha} light is a suitable template for Galactic free-free foreground emission, is found to be in need of reexamination.
- OSTI ID:
- 21474479
- Journal Information:
- Astrophysical Journal, Vol. 724, Issue 2; Other Information: DOI: 10.1088/0004-637X/724/2/1551; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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