Not Just Gas: How Solid-Driven Torques Shaped the Migration of the Galilean Moons

The primary aim of this study is to investigate the orbital migration of the Galilean moons by incorporating self-consistent solid dynamics in circumjovian disk models. We perform two-fluid simulations using the FARGO3D code on a 2D polar grid. The simulations model a satellite with the mass of a proto-moon, Europa, or Ganymede interacting with a circumjovian disk.

The dust component, coupled to the gas via a drag force, is characterized by the dust-to-gas mass ratio (ϵ) and the Stokes number (Ts). The effect of solids fundamentally alter the satellites’ evolution. We identify a vast parameter space where migration is slowed, halted, robustly reversed -leading to outward migration-, or significantly accelerated inward.

The migration rate is dependent on satellite mass, providing a natural source of differential migration. Solid dynamics provides a robust and self-consistent mechanism that fundamentally alters the migration of the Galilean moons, potentially addressing the long-standing migration catastrophe.

This mechanism critically affects the survival of satellites and could offer a viable physical process to explain the establishment of resonances through differential migration. These findings establish that solid torques are a critical, non-negligible factor in shaping the final architecture of satellite systems.

Lucas Gonzalez-Rivas, Leonardo Krapp, Ximena Ramos, Pablo Benitez-Llambay

Comments: 5 pages, 2 figures, submitted to A&A Letter to the editor
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2512.23542 [astro-ph.EP] (or arXiv:2512.23542v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2512.23542
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Submission history
From: Leonardo Krapp
[v1] Mon, 29 Dec 2025 15:31:34 UTC (939 KB)
https://arxiv.org/abs/2512.23542
Astrobiology,