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Title: | The Herschel Comprehensive (U)LIRG Emission Survey (HERCULES): CO Ladders, Fine Structure Lines, and Neutral Gas Cooling | Authors: | Rosenberg, M. J. F. van der Werf, P. P. Aalto, S. Armus, L. Charmandaris, V. Díaz-Santos, T. Evans, A. S. Fischer, J. Gao, Y. González-Alfonso, E. Greve, T. R. Harris, A. I. Henkel, C. Israel, F. P. Isaak, K. G. Kramer, C. Meijerink, R. Naylor, D. A. Sanders, D. B. Smith, H. A. Spaans, M. SPINOGLIO, Luigi Giuseppe Maria Stacey, G. J. Veenendaal, I. Veilleux, S. Walter, F. Weiß, A. Wiedner, M. C. van der Wiel, M. H. D. Xilouris, E. M. |
Issue Date: | 2015 | Journal: | THE ASTROPHYSICAL JOURNAL | Number: | 801 | Issue: | 2 | First Page: | 72 | Abstract: | (Ultra) luminous infrared galaxies ((U)LIRGs) are objects characterized by their extreme infrared (8-1000 μm) luminosities (L <SUB>LIRG</SUB> > 10<SUP>11</SUP> L <SUB>☉</SUB> and L <SUB>ULIRG</SUB> > 10<SUP>12</SUP> L <SUB>☉</SUB>). The Herschel Comprehensive ULIRG Emission Survey (PI: van der Werf) presents a representative flux-limited sample of 29 (U)LIRGs that spans the full luminosity range of these objects (10<SUP>11</SUP> L <SUB>☉</SUB> <= L <SUB>IR</SUB> <= 10<SUP>13</SUP> L <SUB>☉</SUB>). With the Herschel Space Observatory, we observe [C II] 157 μm, [O I] 63 μm, and [O I] 145 μm line emission with Photodetector Array Camera and Spectrometer, CO J = 4-3 through J = 13-12, [C I] 370 μm, and [C I] 609 μm with SPIRE, and low-J CO transitions with ground-based telescopes. The CO ladders of the sample are separated into three classes based on their excitation level. In 13 of the galaxies, the [O I] 63 μm emission line is self absorbed. Comparing the CO excitation to the InfraRed Astronomical Satellite 60/100 μm ratio and to far infrared luminosity, we find that the CO excitation is more correlated to the far infrared colors. We present cooling budgets for the galaxies and find fine-structure line flux deficits in the [C II], [Si II], [O I], and [C I] lines in the objects with the highest far IR fluxes, but do not observe this for CO 4 <= J <SUB>upp</SUB> <= 13. In order to study the heating of the molecular gas, we present a combination of three diagnostic quantities to help determine the dominant heating source. Using the CO excitation, the CO J = 1-0 linewidth, and the active galactic nucleus (AGN) contribution, we conclude that galaxies with large CO linewidths always have high-excitation CO ladders, and often low AGN contributions, suggesting that mechanical heating is important. <P />Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. | Acknowledgments: | We thank Edward Polehampton for his help reducing the SPIRE observations. Basic research in infrared astronomy at the Naval Research Laboratory is funded by the Office of Naval Research. J.F. also acknowledges partial support from the NHSC/JPL subcontract 1371112. SPIRE has been developed by a consortium of institutes led by Cardiff University (UK) and including: University of Lethbridge (Canada); NAOC (China); CEA, LAM (France); IFSI, University of Padua (Italy); IAC (Spain); Stockholm Observatory (Sweden); Imperial College London, RAL, UCL-MSSL, UKATC, University of Sussex (UK); and Caltech, JPL, NHSC, University of Colorado (USA). This development has been supported by national funding agencies: CSA (Canada); NAOC (China); CEA, CNES, CNRS (France); ASI (Italy); MCINN (Spain); SNSB (Sweden); STFC, UKSA (UK); and NASA (USA). The Herschel spacecraft was designed, built, tested, and launched under a contract to ESA managed by the Herschel / Planck Project team by an industrial consortium under the overall responsibility of the prime contractor Thales Alenia Space (Cannes), and including Astrium (Friedrichshafen) responsible for the payload module and for system testing at spacecraft level, Thales Alenia Space (Turin) responsible for the service module, and Astrium (Toulouse) responsible for the telescope, with in excess of a hundred subcontractors. HCSS/HSpot/HIPE is a joint development (are joint developments) by the Herschel Science Ground Segment Consortium, consisting of ESA, the NASA Herschel Science Center, and the HIFI, PACS and SPIRE consortia. H.A.S. acknowledges partial support from NASA grant NNX12AI55G and JPL RSA contract 717437 and 717353. M.H.D.v.d.W. is supported by the Canadian Space Agency (CSA) and the Natural Sciences and Engineering Research Council of Canada (NSERC). | URI: | http://hdl.handle.net/20.500.12386/30912 | URL: | https://iopscience.iop.org/article/10.1088/0004-637X/801/2/72 | ISSN: | 0004-637X | DOI: | 10.1088/0004-637X/801/2/72 | Bibcode ADS: | 2015ApJ...801...72R | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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Rosenberg_2015_ApJ_801_72.pdf | Pdf editoriale | 1.16 MB | Adobe PDF | View/Open |
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