发表机构
University of Maryland; Harvard & Smithsonian; University of North Carolina at Chapel Hill; University of Bologna; INAF, Astrophysics and Space Science Observatory Bologna; Leibniz-Institut für Astrophysik Potsdam (AIP); Leiden University（马里兰大学; 哈佛-史密森尼天体物理中心; 北卡罗来纳大学教堂山分校; 博洛尼亚大学; 意大利国家天体物理研究所博洛尼亚天文台; 波茨坦阿斯特拉物理学莱布尼茨研究所; 莱顿大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文首次系统比较欧拉与拉格朗日MHD代码（ART、RAMSES、AREPO、SWIFT）模拟星系发电机，发现磁场放大强烈依赖数值格式，并证明降低AREPO网格速度可与其他静态网格代码结果一致。
AI 中文摘要
星系磁场被认为是由微观过程（如Biermann电池）所播种，并主要通过发电机过程放大到观测到的微高斯强度。这种放大很可能主要发生在原星系内，其中湍流和旋转动能通过发电机作用转化为磁能。然而，这一过程的两个方面在模拟中仍缺乏约束：放大场的饱和水平以及达到该水平的时间尺度。特别是，不同的数值方法、分辨率策略和亚网格模型尚未收敛到相似的结果，使得难以建立关于星系中发电机放大的鲁棒、与代码无关的结论。在本工作中，我们首次系统地比较了采用多种MHD格式的欧拉和拉格朗日代码，包括ART、RAMSES、AREPO和SWIFT。使用银河系型星系的相同初始条件，且不包含恒星形成和恒星反馈，我们发现星系盘内磁场放大历史强烈依赖于流体动力学格式的选择，欧拉与拉格朗日方法之间存在数量级的差异。我们进一步证明，在移动网格代码AREPO中降低网格速度会导致与使用静态网格代码ART和RAMSES获得的结果一致。这些结果突显了在解释星系模拟中磁场放大时仔细评估数值效应的重要性。
英文摘要
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.
Comments34 pages, 23 figures; submitted to ApJ; comments are welcome
