Title
The Origins of [C II] Emission in Local Star-forming Galaxies
Author
Croxall, K. V. (Ohio State University; Max-Planck-Institut für Astronomie; Illumination Works LLC)
Smith, J. D T (Max-Planck-Institut für Astronomie; University of Toledo)
Pellegrini, E. (University of Toledo; University of Heidelberg)
Groves, Brent (Australian National University)
Bolatto, Alberto (University of Maryland)
Herrera-Camus, Rodrigo (Max Planck Institute for Extraterrestrial Physics Garching)
Sandstrom, K. M. (University of California)
Draine, Bruce (Princeton University)
Wolfire, M. G. (University of Maryland)
Armus, Lee (Spitzer Science Center)
Boquien, Mederic (Universidad de Antofagasta)
Brandl, B.R. (TU Delft Astrodynamics & Space Missions; Universiteit Leiden) 
Dale, Daniel A. (University of Wyoming)
Galametz, Maud (ENS-PSL Research University & CNRS; European Southern Observatory)
Hunt, L. K. (INAF-Osservatorio Astrofisico di Arcetri)
Kennicutt, R. C. (University of Cambridge)
Kreckel, K. (Max-Planck-Institut für Astronomie)
Rigopoulou, D. (University of Oxford)
van der werf, p (Universiteit Leiden)
Wilson, C (McMaster University)
Date
2017-08-20
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+ 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.
Subject
galaxies: ISM
ISM: lines and bands
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http://resolver.tudelft.nl/uuid:5627de75-4675-4bc7-9c77-1b928541239e
DOI
https://doi.org/10.3847/1538-4357/aa8035
ISSN
0004-637X
Source
The Astrophysical Journal: an international review of astronomy and astronomical physics, 845 (2)
Part of collection
Institutional Repository
Document type
journal article
Rights
© 2017 K. V. Croxall, J. D T Smith, E. Pellegrini, Brent Groves, Alberto Bolatto, Rodrigo Herrera-Camus, K. M. Sandstrom, Bruce Draine, M. G. Wolfire, Lee Armus, Mederic Boquien, B.R. Brandl, Daniel A. Dale, Maud Galametz, L. K. Hunt, R. C. Kennicutt, K. Kreckel, D. Rigopoulou, p van der werf, C Wilson