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|Title:||The Origins of [C II] Emission in Local Star-forming Galaxies||Authors:||Croxall, K. V.
Smith, J. D.
Sandstrom, K. M.
Wolfire, M. G.
HUNT, Leslie Kipp
Kennicutt, R., Jr.
van der Werf, P.
|Issue Date:||2017||Journal:||THE ASTROPHYSICAL JOURNAL||Number:||845||Issue:||2||First Page:||96||Abstract:||The [C II] 158 μm fine-structure line is the brightest emission line observed in local star-forming galaxies. As a major coolant of the gas-phase interstellar medium, [C II] balances the heating, including that due to far-ultraviolet photons, which heat the gas via the photoelectric effect. However, the origin of [C II] emission remains unclear because C<SUP>+</SUP> can be found in multiple phases of the interstellar medium. Here we measure the fractions of [C II] emission originating in the ionized and neutral gas phases of a sample of nearby galaxies. We use the [N II] 205 μm fine-structure line to trace the ionized medium, thereby eliminating the strong density dependence that exists in the ratio of [C II]/[N II] 122 μm. Using the FIR [C II] and [N II] emission detected by the KINGFISH (Key Insights on Nearby Galaxies: a Far- Infrared Survey with Herschel) and Beyond the Peak Herschel programs, we show that 60%─80% of [C II] emission originates from neutral gas. We find that the fraction of [C II] originating in the neutral medium has a weak dependence on dust temperature and the surface density of star formation, and has a stronger dependence on the gas-phase metallicity. In metal-rich environments, the relatively cooler ionized gas makes substantially larger contributions to total [C II] emission than at low abundance, contrary to prior expectations. Approximate calibrations of this metallicity trend are provided.||URI:||http://hdl.handle.net/20.500.12386/26744||URL:||https://iopscience.iop.org/article/10.3847/1538-4357/aa8035||ISSN:||0004-637X||DOI:||10.3847/1538-4357/aa8035||Bibcode ADS:||2017ApJ...845...96C||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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checked on Sep 24, 2020
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