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We use new high-resolution H i data from the Australian Square Kilometre Array Pathfinder to investigate the dynamics of the Small Magellanic Cloud (SMC). We model the H i gas component as a rotating disc of non-negligible angular size, moving into the plane of the sky, and undergoing nutation/precession motions. We derive a high-resolution (∼ 10 pc) rotation curve of the SMC out to R ∼ 4kpc⁠. After correcting for asymmetric drift, the circular velocity slowly rises to a maximum value of V_c ≃ 55kms^-1 at R ≃ 2.8kpc and possibly flattens outwards. In spite of the SMC undergoing strong gravitational interactions with its neighbours, its H i rotation curve is akin to that of many isolated gas-rich dwarf galaxies. We decompose the rotation curve and explore different dynamical models to deal with the unknown 3D shape of the mass components (gas, stars, and dark matter). We find that, for reasonable mass-to-light ratios, a dominant dark matter halo with mass M_DM(R < 4kpc) ≃ 1-1.5×10⁹ M_⊙ is always required to successfully reproduce the observed rotation curve, implying a large baryon fraction of 30 per cent - 40 per cent⁠. We discuss the impact of our assumptions and the limitations of deriving the SMC kinematics and dynamics from H i observations.

Item Type:	Refereed Article
Keywords:	galaxies: dwarf; galaxies: kinematics and dynamics; Magellanic Clouds
Research Division:	Physical Sciences
Research Group:	Astronomical sciences
Research Field:	Galactic astronomy
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the physical sciences
UTAS Author:	Dickey, JM (Professor John Dickey)
ID Code:	133221
Year Published:	2019
Web of Science® Times Cited:	26
Deposited By:	Mathematics and Physics
Deposited On:	2019-06-19
Last Modified:	2020-05-20
Downloads:	18 View Download Statistics