The ATLASinline image project – XII. Recovery of the mass-to-light ratio of simulated early-type barred galaxies with axisymmetric dynamical models

Authors

  • Pierre-Yves Lablanche,

    Corresponding author
    1. 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
    2. European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
      E-mail: plablanc@eso.org
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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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  • Eric Emsellem,

    1. 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
    2. European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
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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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  • Leo Michel-Dansac,

    1. 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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  • Katherine Alatalo,

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

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

    1. Observatoire de Paris, LERMA and CNRS, 61 Av. de l’Observatoire, F-75014 Paris, 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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  • 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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  • 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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  • 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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  • 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. European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
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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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  • Richard M. McDermid,

    1. Gemini Observatory, Northern Operations Centre, 670 N. A‘ohoku Place, Hilo, HI 96720, USA
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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. Sub-department of Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH
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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
      Dunlap fellow.
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  • Lisa M. Young

    1. Physics Department, New Mexico Institute of Mining and Technology, Socorro, NM 87801, USA
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E-mail: plablanc@eso.org

Dunlap fellow.

ABSTRACT

We investigate the accuracy in the recovery of the stellar dynamics of barred galaxies when using axisymmetric dynamical models. We do this by trying to recover the mass-to-light ratio (M/L) and the anisotropy of realistic galaxy simulations using the Jeans Anisotropic Multi-Gaussian Expansion (JAM) modelling method. However, given that the biases we find are mostly due to an application of an axisymmetric modelling algorithm to a non-axisymmetric system and in particular to inaccuracies in the deprojected mass model, our results are relevant for general axisymmetric modelling methods. We run N-body collisionless simulations to build a library with various luminosity distribution, constructed to mimic real individual galaxies, with realistic anisotropy. The final result of our evolved library of simulations contains both barred and unbarred galaxies. The JAM method assumes an axisymmetric mass distribution, and we adopt a spatially constant M/L and anisotropy inline image distributions. The models are fitted to two-dimensional maps of the second velocity moments inline image of the simulations for various viewing angles [position angle (PA) of the bar and inclination of the galaxy]. We find that the inclination is generally well recovered by the JAM models, for both barred and unbarred simulations. For unbarred simulations the M/L is also accurately recovered, with negligible median bias and with a maximum one of just Δ(M/L) < 1.5 per cent when the galaxy is not too close to face on. At very low inclinations (inline image) the M/L can be significantly overestimated (9 per cent in our tests, but errors can be larger for very face-on views). This is in agreement with previous studies. For barred simulations the M/L is on average (when PA = 45°) essentially unbiased, but we measure an over/underestimation of up to Δ(M/L) = 15 per cent in our tests. The sign of the M/L bias depends on the PA of the bar as expected: overestimation occurs when the bar is closer to end-on, due to the increased stellar motion along the line-of-sight, and underestimation otherwise. For unbarred simulations, the JAM models are able to recover the mean value of the anisotropy with bias inline image, within the region constrained by the kinematics. However when a bar is present, or for nearly face-on models, the recovered anisotropy varies wildly, with biases up to Δβz≈ 0.3.

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