Mapping the dark matter halo of early-type galaxy NGC 2974 through orbit-based models with combined stellar and cold gas kinematics

Journal Article · 25 November 2019 · Monthly Notices of the Royal Astronomical Society

DOI: https://doi.org/10.1093/mnras/stz3293 · OSTI ID:1579588

Yang, Meng ^[1]; Zhu, Ling  ^[2]; Weijmans, Anne-Marie ^[1]; van de Ven, Glenn  ^[3]; Boardman, Nicholas ^[4]; Morganti, Raffaella  ^[5]; Oosterloo, Tom ^[5]

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1. School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, UK
2. Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, China
3. Department of Astrophysics, University of Vienna, Türkenschanzstrasse 17, Vienna 1180, Austria, European Southern Observatory, Karl-Schwarzschild-Str 2, Garching bei Munchen D-85748, Germany
4. Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
5. Netherlands Institute for Radio Astronomy (ASTRON), Postbus 2, Dwingeloo NL-7990 AA, the Netherlands, Kapteyn Astronomical Institute, University of Groningen, PO Box 800, Groningen NL-9700 AV, the Netherlands

ABSTRACT We present an orbit-based method of combining stellar and cold gas kinematics to constrain the dark matter profile of early-type galaxies. We apply this method to early-type galaxy NGC 2974, using Pan-STARRS imaging and SAURON stellar kinematics to model the stellar orbits, and introducing H i kinematics from VLA observation as a tracer of the gravitational potential. The introduction of the cold gas kinematics shows a significant effect on the confidence limits of especially the dark halo properties: we exclude more than $$95{{\ \rm per\ cent}}$$ of models within the 1σ confidence level of Schwarzschild modelling with only stellar kinematics, and reduce the relative uncertainty of the dark matter fraction significantly to $$10{{\ \rm per\ cent}}$$ within 5Re. Adopting a generalized Navarro–Frenk–White (NFW) dark matter profile, we measure a shallow cuspy inner slope of $$0.6^{+0.2}_{-0.3}$$ when including the cold gas kinematics in our model. We cannot constrain the inner slope with the stellar kinematics alone.

• Sponsoring Organization: USDOE
• OSTI ID: 1579588
• Journal Information: Monthly Notices of the Royal Astronomical Society, Journal Name: Monthly Notices of the Royal Astronomical Society Journal Issue: 3 Vol. 491; ISSN 0035-8711
• Publisher: Oxford University PressCopyright Statement
• Country of Publication: United Kingdom
• Language: English