Towards robust simulations of the galactic dynamo: a cross-code comparison between Eulerian and Lagrangian schemes
Abstract
Galactic magnetic fields are thought to be seeded by microscopic processes such as the Biermann battery and are primarily amplified to observed microgauss strengths by dynamo processes. Much of this amplification likely occurs within proto-galaxies, where turbulent and rotational kinetic energy is converted into magnetic energy via dynamo action. However, two aspects of this process remain poorly constrained in simulations: the saturation level of the amplified field and the timescale on which it is reached. In particular, different numerical methods, resolution strategies, and subgrid prescriptions have not converged to similar results, making it difficult to establish robust, code-independent conclusions about dynamo amplification in galaxies. In this work, we present the first systematic comparison of both Eulerian and Lagrangian codes that employ diverse MHD schemes, including ART, RAMSES, AREPO, and SWIFT. Using identical initial conditions for Milky Way-type galaxies and without including star formation and stellar feedback, we find that the amplification history of the magnetic field within the galactic disk depends strongly on the choice of hydrodynamical scheme, with orders-of-magnitude differences between Eulerian and Lagrangian approaches. We further demonstrate that reducing the mesh velocity in the moving-mesh code AREPO leads to results consistent with those obtained using the static grid codes ART and RAMSES. These results highlight the importance of carefully assessing numerical effects when interpreting magnetic field amplification in galaxy simulations.
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BibTeX
@misc{ugalino2026towards,
title = {{Towards robust simulations of the galactic dynamo: a cross-code comparison between Eulerian and Lagrangian schemes}},
author = {Mark Ivan Ugalino and Benedikt Diemer and Vadim A. Semenov and Jin Young Kim and Federico Marinacci and Christoph Pfrommer and Matthieu Schaller and Nikyta Shchutskyi and Volker Springel and Romain Teyssier and Oliver Zier},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.02308},
eprint = {2610.02308},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.02308},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Towards robust simulations of the galactic dynamo: a cross-code comparison between Eulerian and Lagrangian schemes
AU - Mark Ivan Ugalino
AU - Benedikt Diemer
AU - Vadim A. Semenov
AU - Jin Young Kim
AU - Federico Marinacci
AU - Christoph Pfrommer
AU - Matthieu Schaller
AU - Nikyta Shchutskyi
AU - Volker Springel
AU - Romain Teyssier
AU - Oliver Zier
PY - 2026
DA - 2026/10/01
PB - arXiv
DO - 10.48550/arxiv.2610.02308
UR - https://arxiv.org/abs/2610.02308
AB - Galactic magnetic fields are thought to be seeded by microscopic processes such as the Biermann battery and are primarily amplified to observed microgauss strengths by dynamo processes. Much of this amplification likely occurs within proto-galaxies, where turbulent and rotational kinetic energy is converted into magnetic energy via dynamo action. However, two aspects of this process remain poorly constrained in simulations: the saturation level of the amplified field and the timescale on which it is reached. In particular, different numerical methods, resolution strategies, and subgrid prescriptions have not converged to similar results, making it difficult to establish robust, code-independent conclusions about dynamo amplification in galaxies. In this work, we present the first systematic comparison of both Eulerian and Lagrangian codes that employ diverse MHD schemes, including ART, RAMSES, AREPO, and SWIFT. Using identical initial conditions for Milky Way-type galaxies and without including star formation and stellar feedback, we find that the amplification history of the magnetic field within the galactic disk depends strongly on the choice of hydrodynamical scheme, with orders-of-magnitude differences between Eulerian and Lagrangian approaches. We further demonstrate that reducing the mesh velocity in the moving-mesh code AREPO leads to results consistent with those obtained using the static grid codes ART and RAMSES. These results highlight the importance of carefully assessing numerical effects when interpreting magnetic field amplification in galaxy simulations.
ER -