Tidally induced radial migration waves in Large Magellanic Cloud-like galaxies

¹ Lund Observatory, Division of Astrophysics, Lund University, Box 43, 221 00 Lund, Sweden
² Université de Toulouse, 118 route de Narbonne, 31062 Toulouse Cedex 9, France
³ Departamento de Física de la Tierra y Astrofísica, Fac. de C.C. Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain

^★ Corresponding author: dylan.hebrail@fysik.lu.se

Received: 24 September 2025
Accepted: 24 October 2025

Abstract

Context. Stellar radial migration has predominantly been examined in isolated disc galaxies where non-axisymmetric structures drive the process. By contrast, while tidal interactions are known for having an influence, their contribution remains comparatively under explored. The Large Magellanic Cloud (LMC), the nearest disc galaxy to the Milky Way (MW) and currently interacting with the Small Magellanic Cloud (SMC), provides a unique laboratory to investigate this interplay.

Aims. We aim to quantify the impact of tidal interactions on radial migration and metallicity distribution in high-resolution simulations of LMC-like disc galaxies.

Methods. We leveraged a subsample of KRATOS, a suite of 28 pure N-body simulations of the LMC-SMC-MW system. Specifically, we used six simulations of both isolated and interacting LMC-like galaxies, exploring different values of the Toomre stellar parameter (Q). These simulations allowed us to map the evolution of the stars’ guiding radii, R_g(t), compute radial migration fluxes in interacting systems, and compare them with their isolated counterparts. This in turn allowed us to quantify the link between tidal interactions, radial migration, non-axisymmetric patterns, disc internal stability, and the radial metallicity distribution.

Results. We present tidally triggered wave-like radial migration fluxes reaching up to ∼ 40% of a disc’s stellar mass per gigayear. This wave-like migration appears during the satellite’s pericentre passages, almost independently of Q, and induces a metallicity drop of ∼ 3−5% in the isolated galaxy’s maximum metallicity in the inner disc. Additionally, in the isolated simulations, the extent of variation in the bar’s resonance region coincides with the mixing zones in the metallicity distribution.

Conclusions. We propose a novel description of a wave-like radial migration flux as a dynamical response of a galaxy undergoing tidal interactions and sketch its impact on the galaxy’s metallicity distribution.