Black Hole Flares: Ejection of Accreted Magnetic Flux through 3D Plasmoid-mediated Reconnection
Black Hole Flares: Ejection of Accreted Magnetic Flux through 3D Plasmoid-mediated Reconnection
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DOI：
10.3847/2041-8213/ac46a1
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发表时间：
2021-09
期刊：
影响因子：
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通讯作者：
B. Ripperda;M. Liska;K. Chatterjee;G. Musoke;A. Philippov;S. Markoff;A. Tchekhovskoy;Z. Younsi
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文献类型：
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作者：
B. Ripperda;M. Liska;K. Chatterjee;G. Musoke;A. Philippov;S. Markoff;A. Tchekhovskoy;Z. Younsi
磁重联可以为来自吸积黑洞内部磁层的明亮、快速的耀斑提供动力。我们进行了极高分辨率（5376 × 2304 × 2304 个单元）广义相对论磁流体动力学模拟，首次在 3D 磁滞盘中捕获等离子体介导的重连接。我们表明，在内部几个史瓦西半径内的瞬态、非轴对称、低密度磁层中形成了赤道、等离子体不稳定的电流片。在当前片中，磁通量束通过以通用等离子体介导的速率重新连接从事件视界逃逸。重新连接以射流中高度磁化的等离子体为食，并将最终被困在通量束中的等离子体加热到与射流磁化强度成比例的温度。逃逸的通量束可以作为低密度热点完成一个完整的轨道，这与重力干涉仪对 Sgr A* 的观测结果一致。地平线附近的重新连接产生足够高能的等离子体来解释吸积黑洞的耀斑，例如从 M87 观察到的 TeV 发射。耀斑期间质量吸积率的下降以及由此产生的低密度磁层使得重联加速粒子产生的极高能光子更容易逃逸。极端分辨率导致聚合等离子体介导的重连接率，直接决定耀斑的时间尺度和特性。
Magnetic reconnection can power bright, rapid flares originating from the inner magnetosphere of accreting black holes. We conduct extremely high-resolution (5376 × 2304 × 2304 cells) general-relativistic magnetohydrodynamics simulations, capturing plasmoid-mediated reconnection in a 3D magnetically arrested disk for the first time. We show that an equatorial, plasmoid-unstable current sheet forms in a transient, nonaxisymmetric, low-density magnetosphere within the inner few Schwarzschild radii. Magnetic flux bundles escape from the event horizon through reconnection at the universal plasmoid-mediated rate in this current sheet. The reconnection feeds on the highly magnetized plasma in the jets and heats the plasma that ends up trapped in flux bundles to temperatures proportional to the jet’s magnetization. The escaped flux bundles can complete a full orbit as low-density hot spots, consistent with Sgr A* observations by the GRAVITY interferometer. Reconnection near the horizon produces sufficiently energetic plasma to explain flares from accreting black holes, such as the TeV emission observed from M87. The drop in the mass accretion rate during the flare and the resulting low-density magnetosphere make it easier for very-high-energy photons produced by reconnection-accelerated particles to escape. The extreme-resolution results in a converged plasmoid-mediated reconnection rate that directly determines the timescales and properties of the flare.