标题： 具有现实初始磁场的双中子星合并中的延迟喷流启动 显示英文标题

标题： Delayed jet launching in binary neutron star mergers with realistic initial magnetic fields

摘要： 我们分析了一个寿命较长的超大质量中子星合并残余物（合并后寿命为$>250$毫秒），该残余物是通过使用梯度亚网格模型的大涡模拟获得的。 我们发现了一种清晰的螺旋状磁场结构，该结构由磁场的环向分量主导。 尽管在模拟时间内没有喷流出现，但在后期时间，我们在所有尺度上观察到磁场的极向分量显著增加。 我们还与多个中子星双星模拟的结果进行了比较，这些模拟的分辨率为$120$~m，并演化至合并后$50$~ms，它们在磁场的初始拓扑结构和强度方面有所不同。 我们发现最佳选择是一种各向同性的小尺度磁场分布，它模仿了合并过程中通常发展出的湍流状态。 这种初始配置比通常用于此类模拟的纯偶极子大尺度场更接近我们的高分辨率模拟结果。 这提供了一种进行此类模拟的方法，避免了计算成本高昂的网格，以准确捕捉由开尔文-亥姆霍兹不稳定性引起的磁场增强。 显示英文摘要

摘要： We analyze a long-lived hyper-massive neutron star merger remnant (post-merger lifetime $>250$ ms) that has been obtained via large eddy simulations with a gradient subgrid-scale model. We find a clear helicoidal magnetic field structure that is governed by the toroidal component of the magnetic field. Although no jet emerges during the simulation time, we observe at late times a significant increase of the poloidal component of the magnetic field at all scales. We also compare with the results of several binary neutron star simulations with moderate resolution of $120$~m, that are evolved up to $50$~ms after the merger, which differ in terms of the initial topology and strength of the magnetic field. We find that the best choice is an isotropic small-scale magnetic field distribution that mimics the turbulent state that generically develops during the merger. This initial configuration reaches a closer agreement with our high-resolution simulation results than the purely dipolar large-scale fields that are commonly employed in these type of simulations. This provides a recipe to perform such simulations avoiding the computationally expensive grids required to faithfully capture the amplification of the magnetic field by Kelvin-Helmholtz instabilities.