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The Far Ultra-violet Background

Kulkarni, S. R. (2022) The Far Ultra-violet Background. Publications of the Astronomical Society of the Pacific, 134 (1038). Art. No. 084302. ISSN 0004-6280. doi:10.1088/1538-3873/ac689e.

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The diffuse far-ultraviolet (FUV) background has received considerable attention from astronomers since the 1970s The initial impetus came from the hope of detecting UV radiation from the hot intergalactic medium. The central importance of the FUV background to the physics (heating and ionization) of the diffuse atomic phases motivated the next generation of experiments. The consensus view is that the diffuse FUV emission at high latitudes has three components: stellar FUV reflected by dust grains (diffuse galactic light or DGL), FUV from other galaxies and the intergalactic medium (extra-galactic background light or EBL) and a component of unknown origin (and referred to as the "offset" component). During the 1980s, there was some discussion that decaying dark matter particles produced FUV radiation. In this paper I investigate production of FUV photons by conventional sources: line emission from Galactic Hot Ionized Medium, two-photon emission from the Galactic Warm Ionized Medium and low-velocity shocks, and Lyman-β fluorescence of hydrogen at several locales in the Solar System (the interplanetary medium, the exosphere and the thermosphere of Earth). I conclude that two thirds and arguably all of the offset component can be explained by the sum of the radiation from the processes listed above.

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Kulkarni, S. R.0000-0001-5390-8563
Additional Information:I gratefully acknowledge receiving help from Ronald Reynolds; Michael Shull, University of Colorado at Boulder; E. Sterl Phinney, California Institute of Technology (Caltech); Jayant Murthy, Indian Institute of Astrophysics; Edwin J. Mierkiewicz & Matthew D. Zettergren, Embry-Riddle Aeronautical University; I. I. Baliukin, Space Research Institute (IKI), Moscow; and E. C. Stone, Project Scientist for Voyager Mission; Nikolaus Zen Prusinski, Caltech. For feedback: Ilaria Caiazzo, Caltech; Bruce Draine, Princeton University; Jerry Edelstein & Christopher McKee, University of California at Berkeley; Marc Postman, Space Telescope Science Institute; and Kevian Stassun, Vanderbilt University, Finally, I am most grateful to Robert Benjamin, University of Wisconsin at Madison; Hannah Earnshaw, Caltech; Eran Ofek, Weizmann, Institute of Science; and Michael Shull for careful reading and constructive feedback. Finally, I thank the referee (anonymous) for feedback which resulted in a clearer and shorter paper.
Group:Astronomy Department, Owens Valley Radio Observatory (OVRO)
Issue or Number:1038
Record Number:CaltechAUTHORS:20220908-154351410
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:116607
Deposited By: Melissa Ray
Deposited On:01 Sep 2022 21:26
Last Modified:08 Sep 2022 15:44

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