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Explaining the [C II] 157.7µm Deficit in Luminous Infrared Galaxies - First Results from a Herschel/PACS Study of the GOALS Sample

Díaz-Santos, T. and Armus, L. and Howell, J. H. and Petric, A. O. and Lord, S. and Appleton, P. and Xu, C. K. and Lu, N. and Schulz, B. and Melbourne, J. and Surace, J. A. and Bridge, C. and Chan, B. H. P. (2013) Explaining the [C II] 157.7µm Deficit in Luminous Infrared Galaxies - First Results from a Herschel/PACS Study of the GOALS Sample. Astrophysical Journal, 774 (1). Art. No. 68. ISSN 0004-637X. doi:10.1088/0004-637X/774/1/68.

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We present the first results of a survey of the [C II] 157.7 μm emission line in 241 luminous infrared galaxies (LIRGs) comprising the Great Observatories All-sky Survey (GOALS) sample, obtained with the PACS instrument on board the Herschel Space Observatory. The [C II] luminosities, L_([C II]), of the LIRGs in GOALS range from ∼ 10^7 to 2×10^9 L_⊙. We find that LIRGs show a tight correlation of [C II]/FIR with far-IR flux density ratios, with a strong negative trend spanning from ∼ 10^(−2) to 10^(−4), as the average temperature of dust increases. We find correlations between the [C II]/FIR ratio and the strength of the 9.7 μm silicate absorption feature as well as with the luminosity surface density of the mid-IR emitting region (∑_(MIR)), suggesting that warmer, more compact starbursts have substantially smaller [C II]/FIR ratios. Pure star-forming LIRGs have a mean [C II]/FIR∼ 4 × 10^(−3), while galaxies with low 6.2 μm PAH equivalent widths (EWs), indicative of the presence of active galactic nuclei (AGN), span the full range in [C II]/FIR. However, we show that even when only pure star-forming galaxies are considered, the [C II]/FIR ratio still drops by an order of magnitude, from 10^(−2) to 10^(−3), with ∑_(MIR) and ∑_(IR), implying that the [C II] 157.7 μm luminosity is not a good indicator of the star formation rate (SFR) for most LIRGs, for it does not scale linearly with the warm dust emission most likely associated to the youngest stars. Moreover, even in LIRGs in which we detect an AGN in the mid-IR, the majority (2/3) of galaxies show [C II]/FIR≥ 10^(−3) typical of high 6.2 μm PAH EW sources, suggesting that most AGNs do not contribute significantly to the far-IR emission. We provide an empirical relation between the [C II]/FIR and the specific SFR (SSFR) for star-forming LIRGs. Finally, we present predictions for the starburst size based on the observed [C II] and far-IR luminosities which should be useful for comparing with results from future surveys of high-redshift galaxies with ALMA and CCAT.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Díaz-Santos, T.0000-0003-0699-6083
Armus, L.0000-0003-3498-2973
Petric, A. O.0000-0003-4030-3455
Appleton, P.0000-0002-7607-8766
Xu, C. K.0000-0002-1588-6700
Lu, N.0000-0002-8948-1044
Surace, J. A.0000-0001-7291-0087
Alternate Title:Explaining the [C II] 158µm Deficit in Luminous Infrared Galaxies - First Results from a Herschel/PACS Study of the GOALS Sample
Additional Information:© 2013 American Astronomical Society. Received 2013 February 15; accepted 2013 July 9; published 2013 August 19. We thank the referee for his/her useful comments and suggestions which significantly improved the quality of this paper. We also thank David Elbaz, Alexander Karim, J. D. Smith, Moshe Elitzur, and J. Gracia-Carpio for very fruitful discussions. L. A. acknowledges the hospitality of the Aspen Center for Physics, which is supported by the National Science Foundation Grant No. PHY-1066293. V. C. would like to acknowledge partial support from the EU FP7 Grant PIRSES-GA- 2012-31578. This work is based on observations made with the Herschel Space Observatory, an European Space Agency Cornerstone Mission with science instruments provided by European-led Principal Investigator consortia and significant participation from NASA. The Spitzer Space Telescope is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration, and of NASA’s Astrophysics Data System (ADS) abstract service.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
European Research Council (ERC)PIRSES-GA-2012-31578
Subject Keywords:galaxies: ISM – galaxies: nuclei – galaxies: starburst – infrared: galaxies
Issue or Number:1
Record Number:CaltechAUTHORS:20130723-110443933
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Official Citation:Explaining the [C II]157.7 μm Deficit in Luminous Infrared Galaxies—First Results from a Herschel/PACS Study of the GOALS Sample T. Díaz-Santos et al. 2013 ApJ 774 68
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:39522
Deposited By: Ruth Sustaita
Deposited On:23 Jul 2013 20:41
Last Modified:09 Nov 2021 23:45

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