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arXiv · 1911.11058

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

Meng Yang·Ling Zhu·Anne-Marie Weijmans·Glenn van de Ven·Nicholas Boardman·Raffaella Morganti·Tom Oosterloo
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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 HI 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 $95\%$ of models within the $1-σ$ confidence level of Schwarzschild modelling with only stellar kinematics, and reduce the relative uncertainty of the dark matter fraction significantly to $10\%$ within $5 R_\mathrm{e}$. Adopting a generalized-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.

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Meng Yang, Ling Zhu, Anne-Marie Weijmans, Glenn van de Ven, Nicholas Boardman, Raffaella Morganti, Tom Oosterloo. 2019-11-25. Mapping the dark matter halo of early-type galaxy NGC 2974 through orbit-based models with combined stellar and cold gas kinematics. https://doi.org/10.1093/mnras%2Fstz3293

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