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The Spatially Resolved [CII] Cooling Line Deficit in Galaxies

Smith, J. D. T. and Croxall, Kevin and Draine, Bruce and De Looze, Ilse and Sandstrom, Karin. M. and Armus, Lee and Beirão, Pedro and Bolatto, Alberto and Boquien, Médéric and Brandl, Bernhard and Crocker, Alison and Dale, Daniel A. and Galametz, Maud and Groves, Brent and Helou, George and Herrera-Camus, Roberto and Hunt, Leslie and Kennicutt, Robert and Walter, Fabian and Wolfire, Mark (2017) The Spatially Resolved [CII] Cooling Line Deficit in Galaxies. Astrophysical Journal, 834 (1). Art. No. 5. ISSN 0004-637X.

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We present [C II] 158 μm measurements from over 15,000 resolved regions within 54 nearby galaxies of the Kingfish program to investigate the so-called [C II] "line-cooling deficit" long known to occur in galaxies with different luminosities. The [C II]/TIR ratio ranges from above 1% to below 0.1% in the sample, with a mean value of 0.48 ± 0.21%. We find that the surface density of 24 μm emission dominates this trend, with [C II]/TIR dropping as νl_ν (24 µm) increases. Deviations from this overall decline are correlated with changes in the gas-phase metal abundance, with higher metallicity associated with deeper deficits at a fixed surface brightness. We supplement the local sample with resolved [C II] measurements from nearby luminous infrared galaxies and high-redshift sources from z = 1.8–6.4, and find that star formation rate density drives a continuous trend of deepening [C II] deficit across six orders of magnitude in Σ_(SFR). The tightness of this correlation suggests that an approximate Σ_(SFR) can be estimated directly from global measurements of [C II]/TIR, and a relation is provided to do so. Several low-luminosity active galactic nucleus (AGN) hosts in the sample show additional and significant central suppression of [C II]/TIR, but these deficit enhancements occur not in those AGNs with the highest X-ray luminosities, but instead those with the highest central starlight intensities. Taken together, these results demonstrate that the [C II] line-cooling line deficit in galaxies likely arises from local physical phenomena in interstellar gas.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Smith, J. D. T.0000-0003-1545-5078
Croxall, Kevin0000-0002-5258-7224
Draine, Bruce0000-0002-0846-936X
Sandstrom, Karin. M.0000-0002-4378-8534
Armus, Lee0000-0003-3498-2973
Bolatto, Alberto0000-0002-5480-5686
Boquien, Médéric0000-0003-0946-6176
Crocker, Alison0000-0001-8513-4945
Dale, Daniel A.0000-0002-5782-9093
Galametz, Maud0000-0002-0283-8689
Groves, Brent0000-0002-9768-0246
Helou, George0000-0003-3367-3415
Herrera-Camus, Roberto0000-0002-2775-0595
Hunt, Leslie0000-0001-9162-2371
Kennicutt, Robert0000-0001-5448-1821
Walter, Fabian0000-0003-4793-7880
Wolfire, Mark0000-0003-0030-9510
Additional Information:© 2016. The American Astronomical Society. Received 2016 July 1; revised 2016 November 2; accepted 2016 November 3; published 2016 December 22. This work is based in part on observations made with Herschel, a European Space Agency Cornerstone Mission with significant participation by NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. We thank Steve Hailey-Dunsheath, T. Rawle, and Tanio Diaz-Santos for advanced access to their compiled [C II] data sets. We also thank them, as well as Gordon Stacey, Carl Ferkinhoff, M. Kapala, and R. Decarli, for helpful discussions which improved this work. J.D.S. gratefully acknowledges visiting support from the Alexander von Humboldt Foundation and the Max Planck Institute für Astronomie as well as support from the Research Corporation for Science Advancement through its Cottrell Scholars program.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Alexander von Humboldt FoundationUNSPECIFIED
Max Planck Institute für AstronomieUNSPECIFIED
Cottrell Scholar of Research CorporationUNSPECIFIED
Subject Keywords:dust, extinction; galaxies: ISM; infrared: galaxies; techniques: spectroscopic
Issue or Number:1
Record Number:CaltechAUTHORS:20170213-145705837
Persistent URL:
Official Citation:J. D. T. Smith et al 2017 ApJ 834 5
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:74264
Deposited By: George Porter
Deposited On:13 Feb 2017 23:35
Last Modified:09 Mar 2020 13:18

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