Comparison of the Diffuse Halpha and FUV Continuum Backgrounds: On the Origins of the Diffuse Halpha Background

• Published in: arXiv.org 2011-11
• Main Authors: Kwang-Il Seon, Witt, Adolf, Il-Joong, Kim, Jong-Ho Shinn, Edelstein, Jerry, Kyoung-Wook Min, Han, Wonyong
• Format: Article
• Language: English
• Subjects: Alpha rays; Massive stars; Milky Way Galaxy; Photons; Radiation sources; Radiative transfer; Stars
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1111.2136

We compare the diffuse H\(\alpha\) map of our Galaxy with the FUV (1370-1710\AA) continuum map. The H\(\alpha\) intensity correlates well with the FUV intensity. The H\(\alpha\)/FUV intensity ratio increases in general with the H\(\alpha\) intensity and the FUV hardness ratio (1370-1520\AA\ to 1560-1710\AA), implying that late OB stars may be the main source of the H\(\alpha\) recombination line at high latitudes. The variation of the H\(\alpha\) intensity as a function of the Galactic latitude is also very similar to that of the FUV intensity. The results likely suggest that not only the original radiation sources of the H\(\alpha\) and FUV backgrounds but also the radiative transfer mechanisms responsible for the diffuse backgrounds are largely common. Therefore, we propose a scenario wherein the H\(\alpha\) background at high latitudes is mostly composed of two components, H\(\alpha\) photons produced by in-situ recombination at the ionized regions around late OB stars and dust-scattered light of the H\(\alpha\) photons originating from late OB stars.