A possible common halo of the Magellanic Clouds

Abstract

Recent observational and theoretical studies on the three-dimensional (3D) space motions of the Large and the Small Magellanic Clouds (LMC and SMC, respectively) have strongly suggested that the latest proper motion measurements of the Magellanic Clouds (MCs) are consistent with their orbital evolution models in which the MCs have arrived in the Galaxy quite recently for the first time. The suggested orbital models appear to be seriously inconsistent with the tidal interaction models in which the Magellanic Stream (MS) can be formed as a result of the mutual tidal interaction between the MCs and the Galaxy for the last ~2 Gyr. Based on orbital models of the MCs, we propose that if the MCs have a common diffuse dark halo with the mass larger than ~ 2 * 10^{10} M_sun, the MCs can not only have the present 3D velocities consistent with the latest proper motion measurements but also interact strongly with each other and with the Galaxy for the last 2 Gyr.These results imply that if the observed proper motions of the MCs are true ones of the centers of mass for the MCs, the common halo of the MCs would need to be considered in constructing self-consistent MS formation models. We discuss whether the origin of the possible common halo can be closely associated either with the past binary formation or with the MCs having been in a small group.

13 pages, 4 figures, accepted in ApJL

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• Galaxy And Mass Assembly (GAMA): In Search of Milky-Way Magellanic Cloud Analogues
• Implications of Recent Measurements of the Milky Way Rotation for the Orbit of the Large Magellanic Cloud
• Accretion of the Magellanic system onto the Galaxy
• Chemical Signature of a Major Merger in the Early Formation of Small Magellanic Cloud
• Satellite galaxies in hydrodynamical simulations of Milky Way sized galaxies
• Local ultra faint dwarves as a product of Galactic processing during a Magellanic group infall
• Mapping atomic and diffuse interstellar band absorption across the Magellanic Clouds and the Milky Way
• A Radial Velocity and Calcium Triplet abundance survey of field Small Magellanic Cloud giants
• When was the Large Magellanic Cloud accreted onto the Galaxy ?
• Revisiting the Role of M31 in the Dynamical History of the Magellanic Clouds
• Applying scale-free mass estimators to the Local Group in Constrained Local Universe Simulations
• The influences of the Magellanic Clouds on the Galaxy: Pole shift, warp, and star formation history
• The orbital evolution of UFDs and GCs in an evolving Galactic potential
• Stellar Over-densities in the Outer Halo of the Milky Way
• On interpretation of recent proper motion data for the Large Magellanic Cloud