The Magellanic Edges Survey III. Kinematics of the disturbed LMC outskirts

Abstract

We explore the structural and kinematic properties of the outskirts of the Large Magellanic Cloud (LMC) using data from the Magellanic Edges Survey (MagES) and Gaia EDR3. Even at large galactocentric radii ($8^{\circ }<R<11^{\circ }$), we find the north-eastern LMC disk is relatively unperturbed: its kinematics are consistent with a disk of inclination ~$36.5^{\circ }$ and line-of-nodes position angle ~$145^{\circ }$ east of north. In contrast, fields at similar radii in the southern and western disk are significantly perturbed from equilibrium, with non-zero radial and vertical velocities, and distances significantly in front of the disk plane implied by our north-eastern fields. We compare our observations to simple dynamical models of the Magellanic/Milky Way system which describe the LMC as a collection of tracer particles within a rigid potential, and the Small Magellanic Cloud (SMC) as a rigid Hernquist potential. A possible SMC crossing of the LMC disk plane ~400 Myr ago, in combination with the LMC's infall to the Milky Way potential, can qualitatively explain many of the perturbations in the outer disk. Additionally, we find the claw-like and arm-like structures south of the LMC have similar metallicities to the outer LMC disk ([Fe/H]~-1), and are likely comprised of perturbed LMC disk material. The claw-like substructure is particularly disturbed, with out-of-plane velocities >60 km s${}^{-1}$ and apparent counter-rotation relative to the LMC's disk motion. More detailed N-body models are necessary to elucidate the origin of these southern features, potentially requiring repeated interactions with the SMC prior to ~1 Gyr ago.

Accepted by MNRAS

References in corpus (16)

• galpy: A Python Library for Galactic Dynamics
• Gaia Early Data Release 3: Photometric content and validation
• A distance to the Large Magellanic Cloud that is precise to one per cent
• Are the Magellanic Clouds on their First Passage about the Milky Way?
• Gaia Early Data Release 3 -- Catalogue validation
• The Origin of the Magellanic Stream and Its Leading Arm
• A distance determination to the Small Magellanic Cloud with an accuracy of better than 2 percent based on late-type eclipsing binary stars
• The VMC Survey. XXV. The 3D structure of the Small Magellanic Cloud from Classical Cepheids
• Clouds, Streams and Bridges. Redrawing the blueprint of the Magellanic System with Gaia DR1
• Gaia Early Data Release 3: The Galactic anticentre
• Revealing the tidal scars of the Small Magellanic Cloud
• Magellanic Mayhem: Metallicities and Motions
• A SkyMapper view of the Large Magellanic Cloud: The dynamics of stellar populations
• Stellar substructures in the periphery of the Magellanic Clouds with the VISTA Hemisphere Survey from the red clump and other tracers
• The VMC Survey -- XL. Three-dimensional structure of the Small Magellanic Cloud as derived from red clump stars
• The Magellanic Edges Survey I. Description and First Results

Cited by in corpus (15)

• What Causes The Formation of Disks and End of Bursty Star Formation?
• The effect of the LMC on the Milky Way system
• Kinematic analysis of the Large Magellanic Cloud using Gaia DR3
• Vertical structure and kinematics of the LMC disc from SDSS/Gaia
• The Magellanic Edges Survey IV. Complex tidal debris in the SMC outskirts
• Equilibrium dynamical models in the inner region of the Large Magellanic Cloud based on Gaia DR3 kinematics
• Lessons from the Magellanic System and its modeling
• The Magellanic Clouds are very rare in the IllustrisTNG simulations
• The SkyMapper search for extremely metal-poor stars in the Large Magellanic Cloud
• Response of the LMC's Bar to a Recent SMC Collision and Implications for the SMC's Dark Matter Profile
• The VMC survey -- LIV. The internal kinematics of the LMC with new VISTA observations
• The 3D kinematics of stellar substructures in the periphery of the Large Magellanic Cloud
• A Galactic Transformation -- Understanding the SMC's Structural and Kinematic Disequilibrium
• Magellanic System Stars Identified in SMACS J0723.3-7327 James Webb Space Telescope Early Release Observations Images
• Hubble Space Telescope proper motions of Large Magellanic Cloud star clusters -- II. Kinematic structure of young and intermediate-age clusters