The origins of (C ii) emission in local star-forming galaxies
The [C ii ] 158 μ m 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. Howev...
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| Main Authors: | , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
2017 August 16
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| In: |
The astrophysical journal
Year: 2017, Volume: 845, Issue: 2 |
| ISSN: | 1538-4357 |
| DOI: | 10.3847/1538-4357/aa8035 |
| Online Access: | Verlag, kostenfrei, Volltext: http://dx.doi.org/10.3847/1538-4357/aa8035 Verlag, Volltext: http://stacks.iop.org/0004-637X/845/i=2/a=96 
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| Author Notes: | K.V.Croxall, J.D.Smith, E.Pellegrini, B.Groves, A.Bolatto, R.Herrera-Camus, K.M.Sandstrom, B.Draine, M.G. Wolfire, L. Armus, M.Boquien, B.Brandl, D.Dale, M.Galametz, L.Hunt, R. Kennicutt Jr, K.Kreckel, D.Rigopoulou, P.van der Werf and C.Wilson |
| Summary: | The [C ii ] 158 μ m 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 + 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 μ m 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 μ m. 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. |
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| Item Description: | Gesehen am 04.04.2018 |
| Physical Description: | Online Resource |
| ISSN: | 1538-4357 |
| DOI: | 10.3847/1538-4357/aa8035 |