EXPLAINING THE [C II]157.7 μm DEFICIT IN LUMINOUS INFRARED GALAXIES—FIRST RESULTS FROM AHERSCHEL/PACS STUDY OF THE GOALS SAMPLE
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- 19 August 2013
- journal article
- research article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 774 (1), 68
- https://doi.org/10.1088/0004-637x/774/1/68
Abstract
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 LIRG 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 ~107 to 2 × 109 L ☉. We find that LIRGs show a tight correlation of [C II]/FIR with far-IR (FIR) 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 (ΣMIR), 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 polycyclic aromatic hydrocarbon (PAH) equivalent widths (EWs), indicative of the presence of active galactic nuclei (AGNs), 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 ΣMIR and ΣIR, implying that the [C II]157.7 μm luminosity is not a good indicator of the star formation rate (SFR) for most local 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 FIR emission. We provide an empirical relation between the [C II]/FIR and the specific SFR for star-forming LIRGs. Finally, we present predictions for the starburst size based on the observed [C II] and FIR luminosities which should be useful for comparing with results from future surveys of high-redshift galaxies with ALMA and CCAT.This publication has 80 references indexed in Scilit:
- The merger Seyfert galaxy Arp 220: line and continuum absorption and emissionMonthly Notices of the Royal Astronomical Society, 2012
- A STUDY OF HEATING AND COOLING OF THE ISM IN NGC 1097 WITHHERSCHEL-PACS ANDSPITZER-IRSThe Astrophysical Journal, 2012
- LOCAL LUMINOUS INFRARED GALAXIES. II. ACTIVE GALACTIC NUCLEUS ACTIVITY FROMSPITZER/INFRARED SPECTROGRAPH SPECTRAThe Astrophysical Journal, 2011
- Building the cosmic infrared background brick by brick withHerschel/PEPAstronomy & Astrophysics, 2011
- DUST-BOUNDED ULTRALUMINOUS INFRARED GALAXIES: MODEL PREDICTIONS FOR INFRARED SPECTROSCOPIC SURVEYSThe Astrophysical Journal, 2009
- GOALS: The Great Observatories All-Sky LIRG SurveyPublications of the Astronomical Society of the Pacific, 2009
- A Compendium of Far‐Infrared Line and Continuum Emission for 227 Galaxies Observed by theInfrared Space ObservatoryThe Astrophysical Journal Supplement Series, 2008
- The Infrared Luminosity Function of Galaxies at Redshiftsz= 1 andz∼ 2 in the GOODS FieldsThe Astrophysical Journal, 2007
- Observations of Ultraluminous Infrared Galaxies with the Infrared Spectrograph on theSpitzer Space Telescope. II. TheIRASBright Galaxy SampleThe Astrophysical Journal, 2007
- ISOLWS Spectroscopy of M82: A Unified Evolutionary ModelThe Astrophysical Journal, 1999