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arXiv · 2503.13039

The VMC survey -- LIV. The internal kinematics of the LMC with new VISTA observations

S. Vijayasree·F. Niederhofer·M. -R. L. Cioni·L. Cullinane·K. Bekki·J. Th. van Loon·N. Kacharov·R. de Grijs·V. D. Ivanov·J. M. Oliveira·F. Dresbach·M. A. T. Groenewegen·D. Erkal
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Abstract

Context: Studying the internal kinematics of galaxies provides insights into their past evolution, current dynamics, and future trajectory. The Large Magellanic Cloud (LMC), as the largest and one of the nearest satellite galaxies of the Milky Way, presents unique opportunities to investigate these phenomena in great detail. In this study, we investigate the internal kinematics of the LMC by deriving precise stellar proper motions using data from the VISTA survey of the Magellanic Clouds system (VMC). The main objective is to refine the LMC's dynamical parameters using improved proper motion measurements, including one additional epoch of VISTA observations, which extended the time baseline from ~ 2 to 10 years. The precision of the proper motion was enhanced, reducing uncertainties from 6 mas/yr to 1.5 mas/yr. We derived geometrical and kinematic parameters, generating velocity maps and rotation curves, for both young and old stellar populations. Finally, we compared a suite of dynamical models, which simulate the interaction of the LMC with the Milky Way and Small Magellanic Cloud (SMC), against the observations. The tangential rotation curve reveals an asymmetric drift between young and old stars, while the radial velocity curve for the young population shows an increasing trend within the inner bar region, suggesting non-circular orbits. We confirm the clockwise rotation around the dynamical centre of the LMC, consistent with previous predictions. A significant residual motion was detected toward the north-east of the LMC, directed away from the centre. This feature observed in the inner disk region is kinematically connected with a substructure identified in the periphery known as Eastern Substructure 1. This motion suggests a possible tidal influence from the Milky Way, combined with the effects of the recent close pericentre passage of the SMC ~150 Myr ago.

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S. Vijayasree, F. Niederhofer, M. -R. L. Cioni, L. Cullinane, K. Bekki, J. Th. van Loon, N. Kacharov, R. de Grijs, V. D. Ivanov, J. M. Oliveira, F. Dresbach, M. A. T. Groenewegen, D. Erkal. 2025-08-11. The VMC survey -- LIV. The internal kinematics of the LMC with new VISTA observations. https://doi.org/10.1051/0004-6361%2F202453145

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