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The Origins of [C II] Emission in Local Star-forming Galaxies

Croxall, K. V. and Smith, J. D. and Pellegrini, E. and Groves, B. and Bolatto, A. and Herrera-Camus, R. and Sandstrom, K. M. and Draine, B. and Wolfire, M. G. and Armus, L. and Boquien, M. and Brandl, B. and Dale, D. and Galametz, M. and Hunt, L. and Kennicutt, R. and Kreckel, K. and Rigopoulou, D. and van der Werf, P. and Wilson, C. (2017) The Origins of [C II] Emission in Local Star-forming Galaxies. Astrophysical Journal, 845 (2). Art. No. 96. ISSN 1538-4357. doi:10.3847/1538-4357/aa8035.

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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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Croxall, K. V.0000-0002-5258-7224
Smith, J. D.0000-0003-1545-5078
Groves, B.0000-0002-9768-0246
Bolatto, A.0000-0002-5480-5686
Herrera-Camus, R.0000-0002-2775-0595
Sandstrom, K. M.0000-0002-4378-8534
Draine, B.0000-0002-0846-936X
Wolfire, M. G.0000-0003-0030-9510
Armus, L.0000-0003-3498-2973
Boquien, M.0000-0003-0946-6176
Dale, D.0000-0002-5782-9093
Galametz, M.0000-0002-0283-8689
Hunt, L.0000-0001-9162-2371
Kennicutt, R.0000-0001-5448-1821
Kreckel, K.0000-0001-6551-3091
Rigopoulou, D.0000-0001-6854-7545
van der Werf, P.0000-0001-5434-5942
Wilson, C.0000-0001-5817-0991
Additional Information:© 2017 The American Astronomical Society. Received 2017 June 2; revised 2017 July 3; accepted 2017 July 6; published 2017 August 16. K.V.C. would like to thank T. Diaz-Santos, G. Accurso, R. Pogge, and P. Goldsmith for their useful discussions regarding this work. K.V.C. acknowledges support from the Deutsche Forschungsgemeinschaft Priority Program ISM-SPP 1573 and the MPIA, and thanks the KINGFISH & BTP teams for their support. J.D.S. acknowledges visiting support from the Alexander von Humboldt Foundation and the MPIA. B.G. acknowledges the support of the Australian Research Council via a Future Fellowship (FT140101202). A.D.B. acknowledges partial support from NSF-AST0955836 and 1412419. B.T.D. acknowledges partial support from NSF-AST1408723. M.B. was supported by MINEDUC-UA project, code ANT 1655. Beyond the Peak research has been supported by a NASA/JPL grant (RSA 1427378). HIPE is a joint development by the Herschel Science Ground Segment Consortium, consisting of ESA, the NASA Herschel Science Center, and the HIFI, PACS, and SPIRE consortia. This work is based on observations made with Herschel, a ESA Cornerstone Mission with significant participation by NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. This research has made use of the NASA/IPAC Extragalactic Database which is operated by JPL/Caltech, under contract with NASA.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Deutsche Forschungsgemeinschaft (DFG)ISM-SPP 1573
Max Planck Institute for Astronomy (MPIA)UNSPECIFIED
Alexander von Humboldt FoundationUNSPECIFIED
Australian Research CouncilFT140101202
MINEDUC-UA ProjectANT 1655
Subject Keywords:galaxies: ISM; ISM: lines and bands
Issue or Number:2
Record Number:CaltechAUTHORS:20170816-093703982
Persistent URL:
Official Citation:K. V. Croxall et al 2017 ApJ 845 96
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:80473
Deposited By: Tony Diaz
Deposited On:16 Aug 2017 17:00
Last Modified:15 Nov 2021 19:36

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