The VMC survey

XLV. Proper motion of the outer LMC and the impact of the SMC^⋆,⋆⋆

¹ Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
e-mail: tschmidt@aip.de
² Institut für Physik und Astronomie, Universität Potsdam, Haus 28, Karl-Liebknecht-Str. 24/25, 14476 Golm, Potsdam, Germany
³ ICRAR, M468, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia
⁴ Department of Physics and Astronomy, Macquarie University, Balaclava Road, Sydney, NSW 2109, Australia
⁵ Research Centre for Astronomy, Astrophysics and Astrophotonics, Macquarie University, Balaclava Road, Sydney, NSW 2109, Australia
⁶ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
⁷ Lennard-Jones Laboratories, School of Chemical and Physical Sciences, Keele University, Keele ST5 5BG, UK
⁸ INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Naples, Italy

Received: 3 September 2021
Accepted: 20 January 2022

Abstract

Context. The Large Magellanic Cloud (LMC) is the most luminous satellite galaxy of the Milky Way and, owing to its companion, the Small Magellanic Cloud (SMC), represents an excellent laboratory to study the interaction of dwarf galaxies.

Aims. The aim of this study is to investigate the kinematics of the outer regions of the LMC by using stellar proper motions to understand the impact of interactions, for example with the SMC about 250 Myr ago.

Methods. We calculate proper motions using multi-epoch K_s-band images from the VISTA survey of the Magellanic Cloud system (VMC). Observations span a time baseline of 2−5 yr. We combine the VMC data with data from the Gaia Early Data Release 3 and introduce a new method to distinguish between Magellanic and Milky Way stars based on a machine learning algorithm. This new technique enables a larger and cleaner sample selection of fainter sources as it reaches below the red clump of the LMC.

Results. We investigate the impact of the SMC on the rotational field of the LMC and find hints of stripped SMC debris. The south-eastern region of the LMC shows a slow rotational speed compared to the overall rotation. N-body simulations suggest that this could be caused by a fraction of stripped SMC stars located in that particular region that move opposite to the expected rotation.