AI 中文总结
研究新生中子星中超临界吸积后的小尺度发电机，通过六个局部三维电阻磁流体动力学模拟，探索不同参数影响，发现磁场能有效放大，饱和磁能低于均分，中微子冷却影响小，支持磁场重新出现情景。
AI 中文摘要
超临界回落吸积可将新生中子星的表面磁场平流到新吸积的外层。在这些物质加入固态地壳并进入霍尔 - 欧姆状态之前，部分物质可能保持热、密且液态，允许湍流磁放大。我们使用FLASH 4.7在具有外部强迫亚声速湍流的周期性域中进行了六个局部三维电阻磁流体动力学模拟，研究在这些条件下小尺度发电机（SSD）是否能运行。我们探索了约700至3700的磁雷诺数，并研究了状态方程、中微子冷却和数值分辨率的影响。磁场从初始强度1e12 G呈指数增长，并在几毫秒内饱和至约(3 - 7)e13 G。饱和磁能保持低于均分，磁动能比约为0.2 - 0.3，与磁普朗特数接近1时的SSD行为一致。128^3和256^3分辨率的参考模拟结果在百分之几的范围内一致。中微子冷却在模拟时间内影响很小，而状态方程仅微弱改变发电机特性。这些结果表明局部SSD可在液态超临界吸积后层中有效放大磁场，并支持新生中子星磁场重新出现的情景。
英文摘要
Hypercritical fallback accretion can advect the surface magnetic field of a newborn neutron star into the newly accreted outer layers. Before this material joins the solid crust and enters the Hall-Ohmic regime, part of it may remain hot, dense, and liquid, allowing turbulent magnetic amplification. We investigate whether a small-scale dynamo (SSD) can operate under these conditions using six local 3D resistive MHD simulations performed with FLASH 4.7 in a periodic domain with externally forced subsonic turbulence. We explore magnetic Reynolds numbers from about 700 to 3700 and examine the effects of the equation of state, neutrino cooling, and numerical resolution. The magnetic field grows exponentially from an initial strength of 1e12 G and saturates at about (3-7)e13 G within milliseconds. The saturated magnetic energy remains below equipartition, with magnetic-to-kinetic energy ratios of about 0.2-0.3, consistent with SSD behavior for magnetic Prandtl number near unity. The reference simulations at 128^3 and 256^3 resolution agree within a few percent. Neutrino cooling has little effect over the simulated times, while the equation of state only weakly modifies the dynamo properties. These results indicate that a local SSD can efficiently amplify magnetic fields in the liquid post-hypercritical accretion layer and support scenarios for magnetic field reemergence in newborn neutron stars.
Journal refJournal of High Energy Astrophysics 55 (2027) 100712
DOI：10.1016/j.jheap.2026.100712
