A Resolution Study of Magnetically Arrested Disks
A Resolution Study of Magnetically Arrested Disks
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DOI：
10.3847/1538-4357/ab0c0c
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发表时间：
2019-03
期刊：
影响因子：
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通讯作者：
C. White;J. Stone;E. Quataert
中科院分区：
文献类型：
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作者：
C. White;J. Stone;E. Quataert
我们研究了模拟旋转黑洞周围磁阻止盘的数值收敛问题。使用广义相对论磁流体力学程序Athena++，我们研究了同一系统在四种分辨率(最高可达512×256×512个晶胞)和两种不同的空间重建算法。整个模拟过程中，吸积率和流动的一般大尺度结构是一致的。这包括在饱和状态中积累的磁通量的量，以及随之而来的从强场中抑制磁致旋转不稳定性。喷流的能量和通过Blandford-Znajek过程提取自旋能量的效率也显示出收敛。然而，喷流的空间结构在所用的一组网格上显示出变化，洛伦兹因子也是如此。由相关长度测量的湍流的小尺度特征并不完全收敛。尽管流动的许多方面都收敛了，但对同步辐射的模拟表明，变率并不收敛，即使在我们的最高分辨率下，变化也会随着分辨率的增加而减少。
We investigate numerical convergence in simulations of magnetically arrested disks around spinning black holes. Using the general-relativistic magnetohydrodynamics code Athena++, we study the same system at four resolutions (up to an effective 512 × 256 × 512 cells) and with two different spatial reconstruction algorithms. The accretion rate and general large-scale structure of the flow agree across the simulations. This includes the amount of magnetic flux accumulated in the saturated state and the ensuing suppression of the magnetorotational instability from the strong field. The energy of the jet and the efficiency with which spin energy is extracted via the Blandford–Znajek process also show convergence. However the spatial structure of the jet shows variation across the set of grids employed, as do the Lorentz factors. Small-scale features of the turbulence, as measured by correlation lengths, are not fully converged. Despite convergence of a number of aspects of the flow, modeling of synchrotron emission shows that variability is not converged and decreases with increasing resolution even at our highest resolutions.