AI 中文总结
本文提出新颖的宇宙学平滑粒子磁流体动力学公式，实现于开源代码SWIFT，通过改进正则化技术提升稳定性，在三个挑战性天体物理应用中展现出良好性能，首次实现EAGLE模型与磁流体求解器的耦合。
AI 中文摘要
我们提出了一种新颖的宇宙学平滑粒子磁流体动力学（SPMHD）公式，旨在对大量非线性天体物理系统中的磁场物理进行建模，且已将其实现于高度并行、完全模块化的开源模拟代码SWIFT中。我们的数值方案旨在以最小的计算成本提供最优性能，保持较低的内存占用，最显著的是能与星系形成的有效亚分辨率配方稳健耦合。这通过将演化方程表示为密度-能量守恒形式，并添加针对高动态范围模拟定制的间断捕获项来实现，这些项进一步由自适应开关调节，极大改善了与亚网格模型的耦合并限制了虚假耗散。此外，我们针对现代SPMHD中使用的两种主要正则化技术提出了新建议，即拉伸不稳定性校正和双曲/抛物型混合散度清洁方案，以确保代码在高动态场景下的稳定性。我们在一系列复杂度递增的问题上评估了该方法的性能，最终以三个无网格方法历史上颇具挑战性的天体物理应用作为收尾：我们研究了原恒星核形成过程中的喷流发射、大质量星系团中的发电机放大，以及类银河系盘星系中的磁场演化；后者是首次报道的EAGLE星系形成模型与磁流体动力学求解器的耦合。在整个测试套件中固定模型超参数以清晰呈现该方法在生产中的能力，我们证明了其在标准“实验室”数值实验中具有良好的性能和分辨率收敛性，且在实际应用中具备竞争力。
英文摘要
We introduce a novel formulation of cosmological smoothed particle magnetohydrodynamics (SPMHD), designed to model magnetic field physics in a vast array of nonlinear astrophysical systems, and which we have implemented in the highly-parallel, entirely modular, and open-source simulation code SWIFT. Our numerical scheme is designed to offer optimal performance at a minimal computational cost, keep a low memory footprint, and most notably couple robustly to effective sub-resolution recipes of galaxy formation. This is achieved through expressing our evolution equations in a density-energy conservative form, and augmenting them with discontinuity-capturing terms tailored to high dynamic range simulations, which are further modulated by adaptive switches that drastically improve coupling to sub-grid models and limit spurious dissipation. We moreover present novel suggestions for the two major regularisation techniques used in modern SPMHD, namely a tensile instability correction and mixed hyperbolic/parabolic divergence-cleaning scheme, to ensure code stability in highly dynamical scenarios. We evaluate the performance of our method on a series of problems of increasing complexity, culminating in three astrophysical applications which have historically proven challenging for mesh-less methods: we study jet launching from a forming proto-stellar core, dynamo amplification in a massive galaxy cluster and magnetic field evolution in a Milky Way-like disk galaxy; the latter constitutes the first reported coupling of the EAGLE galaxy formation model to a magnetohydrodynamics solver. Keeping model hyperparameters fixed across our test suite to provide a transparent picture of our method's capabilities in production, we demonstrate sound performance and convergence with resolution on standard `laboratory' numerical experiments, as well as competitive capabilities in realistic applications.
Comments64 pages, 33 figures, submitted for publication in MNRAS
