The Properties of Reconnection Current Sheets in GRMHD Simulations of Radiatively Inefficient Accretion Flows
The Properties of Reconnection Current Sheets in GRMHD Simulations of Radiatively Inefficient Accretion Flows
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DOI：
10.3847/1538-4357/aaa42f
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发表时间：
2018-02-01
影响因子：
4.9
通讯作者：
Sironi, Lorenzo
中科院分区：
文献类型：
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作者：
Ball, David;Ozel, Feryal;Sironi, Lorenzo
非理想磁流体动力学（MHD）效应可能在确定黑洞上辐射效率低的吸积流的动力学、热性质和观测特征方面发挥重要作用。特别是，磁重联事件期间的粒子加速可能会影响黑洞光谱和耀斑性质。我们使用具有代表性的广义相对论磁流体动力学（GRMHD）模拟黑洞吸积流，以确定和探索的结构和性能的电流片磁重联的潜在网站。在标准和正常演化（SANE）盘的情况下，我们发现在重联点，等离子体β在0.1到1000之间，磁化强度在10（-4）到1之间，并且与重联场相比，引导场很弱。在磁制动（MAD）盘中，我们发现等离子体β的典型值从10（-2）到10（3），磁化强度从10（-3）到10，并且通常具有更强的引导场，其强度与重连场相当或更大。这些都是关键的参数，管理的电子能量分布所产生的磁重联，并可用于等离子体模拟的背景下，提供微观物理输入全球模拟。我们还发现，在重联区域有充足的磁能，为从银河系中心黑洞观察到的明亮X射线耀斑的能量提供动力。
Non-ideal magnetohydrodynamic (MHD) effects may play a significant role in determining the dynamics, thermal properties, and observational signatures of radiatively inefficient accretion flows onto black holes. In particular, particle acceleration during magnetic reconnection events may influence black hole spectra and flaring properties. We use representative general relativistic magnetohydrodynamic (GRMHD) simulations of black hole accretion flows to identify and explore the structures and properties of current sheets as potential sites of magnetic reconnection. In the case of standard and normal evolution (SANE) disks, we find that in the reconnection sites, the plasma beta ranges from 0.1 to 1000, the magnetization ranges from 10(-4) to 1, and the guide fields are weak compared with the reconnecting fields. In magnetically arrested (MAD) disks, we find typical values for plasma beta from 10(-2) to 10(3), magnetizations from 10(-3) to 10, and typically stronger guide fields, with strengths comparable to or greater than the reconnecting fields. These are critical parameters that govern the electron energy distribution resulting from magnetic reconnection and can be used in the context of plasma simulations to provide microphysics inputs to global simulations. We also find that ample magnetic energy is available in the reconnection regions to power the fluence of bright X-ray flares observed from the black hole in the center of the Milky Way.