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The ATLAS3D project – XI. Dense molecular gas properties of CO-luminous early-type galaxies

Authors

  • Alison Crocker,

    Corresponding author
    1. Department of Astronomy, University of Massachusetts, Amherst, MA 01003, USA
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  • Melanie Krips,

    1. Institut de Radio Astronomie Millimétrique (IRAM), Domaine Universitaire, 300 rue de la Piscine, 38406 Saint Martin d’Hères, France
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  • Martin Bureau,

    1. Sub-department of Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH
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  • Lisa M. Young,

    1. Department of Physics, New Mexico Institute of Mining and Technology, Socorro, NM 87801, USA
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  • Timothy A. Davis,

    1. Sub-department of Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH
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  • Estelle Bayet,

    1. Sub-department of Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH
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  • Katherine Alatalo,

    1. Department of Astronomy, University of California, Campbell Hall, Berkeley, CA 94720, USA
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  • Leo Blitz,

    1. Department of Astronomy, University of California, Campbell Hall, Berkeley, CA 94720, USA
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  • Maxime Bois,

    1. European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
    2. Université Lyon 1, Observatoire de Lyon, Centre de Recherche Astrophysique de Lyon and Ecole Normale Supérieure de Lyon, 9 Avenue Charles André, F-69230 Saint-Genis Laval, France
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  • Frédéric Bournaud,

    1. Laboratoire AIM Paris-Saclay, CEA/IRFU/SAp – CNRS – Université Paris Diderot, 91191 Gif-sur-Yvette Cedex, France
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  • Michele Cappellari,

    1. Sub-department of Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH
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  • Roger L. Davies,

    1. Sub-department of Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH
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  • P. T. de Zeeuw,

    1. European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
    2. Sterrewacht Leiden, Leiden University, Postbus 9513, 2300 RA Leiden, the Netherlands
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  • Pierre-Alain Duc,

    1. Laboratoire AIM Paris-Saclay, CEA/IRFU/SAp – CNRS – Université Paris Diderot, 91191 Gif-sur-Yvette Cedex, France
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  • Eric Emsellem,

    1. European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
    2. Université Lyon 1, Observatoire de Lyon, Centre de Recherche Astrophysique de Lyon and Ecole Normale Supérieure de Lyon, 9 Avenue Charles André, F-69230 Saint-Genis Laval, France
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  • Sadegh Khochfar,

    1. Max-Planck Institut für Extraterrestrische Physik, PO Box 1312, D-85478 Garching, Germany
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  • Davor Krajnović,

    1. European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
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  • Harald Kuntschner,

    1. Space Telescope European Coordinating Facility, European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
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  • Pierre-Yves Lablanche,

    1. European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
    2. Université Lyon 1, Observatoire de Lyon, Centre de Recherche Astrophysique de Lyon and Ecole Normale Supérieure de Lyon, 9 Avenue Charles André, F-69230 Saint-Genis Laval, France
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  • Richard M. McDermid,

    1. Gemini Observatory, Northern Operations Centre, 670 N. A‘ohoku Place, Hilo, HI 96720, USA
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  • Raffaella Morganti,

    1. Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo, the Netherlands
    2. Kapteyn Astronomical Institute, University of Groningen, Postbus 800, 9700 AV Groningen, the Netherlands
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  • Thorsten Naab,

    1. Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany
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  • Tom Oosterloo,

    1. Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo, the Netherlands
    2. Kapteyn Astronomical Institute, University of Groningen, Postbus 800, 9700 AV Groningen, the Netherlands
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  • Marc Sarzi,

    1. Centre for Astrophysics Research, University of Hertfordshire, Hatfield, Herts AL1 9AB
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  • Nicholas Scott,

    1. Centre for Astrophysics and Supercomputing, Swinburne University of Technology, PO Box 218, Hawthorn, VIC 3122, Australia
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  • Paolo Serra,

    1. Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, 7990 AA Dwingeloo, the Netherlands
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  • Anne-Marie Weijmans

    Corresponding author
    1. Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St George Street, Toronto, ON M5S 3H4, Canada
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Based on observations carried out with the IRAM 30-m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).

E-mail: crocker@astro.umass.edu

Dunlap fellow.

ABSTRACT

Surveying 18 12CO-bright galaxies from the ATLAS3D early-type galaxy sample with the Institut de Radio Astronomie Millimétrique (IRAM) 30-m telescope, we detect 13CO(1–0) and 13CO(2–1) in all 18 galaxies, HCN(1–0) in 12/18 and HCO+(1–0) in 10/18. We find that the line ratios 12CO(1–0)/13CO(1–0) and 12CO(1–0)/HCN(1–0) are clearly correlated with several galaxy properties: total stellar mass, luminosity-weighted mean stellar age, molecular-to-atomic gas ratio, dust temperature and dust morphology. We suggest that these correlations are primarily governed by the optical depth in the 12CO lines; interacting, accreting and/or starbursting early-type galaxies have more optically thin molecular gas while those with settled dust and gas discs host optically thick molecular gas. The ranges of the integrated line intensity ratios generally overlap with those of spirals, although we note some outliers in the 12CO(1–0)/13CO(1–0), 12CO(2–1)/13CO(2–1) and HCN/HCO+(1–0) ratios. In particular, three galaxies are found to have very low 12CO(1–0)/13CO(1–0) and 12CO(2–1)/13CO(2–1) ratios. Such low ratios may signal particularly stable molecular gas which creates stars less efficiently than ‘normal’ (i.e. below Schmidt–Kennicutt prediction), consistent with the low dust temperatures seen in these galaxies.

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