Magnetosphere of a Kerr black hole immersed in magnetized plasma and its perturbative mode structure
Magnetosphere of a Kerr black hole immersed in magnetized plasma and its perturbative mode structure
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DOI：
10.1103/physrevd.91.124055
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发表时间：
2015-03
影响因子：
5
通讯作者：
Huan Yang;Fan Zhang;L. Lehner
中科院分区：
文献类型：
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作者：
Huan Yang;Fan Zhang;L. Lehner
这项工作研究了在均匀磁化的无力等离子体中，围绕着一个缓慢旋转的黑洞的类似喷流的电磁配置。在这项工作的第一部分，我们提出了一个家庭的固定解决方案，是喷气能力。虽然这些解决方案都满足无力方程和适当的边界条件，我们的数值实验表明，从不同的初始数据开始，一个独特的松弛状态，因此家庭的一个成员可能是优于其他人。在这项工作的第二部分中，我们分析了这个家庭的射流解决方案的扰动，并表明，扰动模式表现出类似的分裂到捕获和旅行类先前发现扰动Blandford-Znajek解决方案。在程函极限下，俘获模可以用无力等离子体中的快磁声波来识别，行波本质上是阿尔芬波。此外，在我们的分析范围内，我们还没有看到不稳定模式的迹象，在光交叉的时间尺度的系统，其中发生的数值弛豫过程。这种观察不利于模式不稳定性作为挑选出一个优选的解决方案的选择机制。因此，我们的分析研究无法从族中明确选择特定的解决方案作为上述优选的最终状态。这仍然是一个有趣的开放问题。
This work studies jet-like electromagnetic configurations surrounding a slowly-spinning black-hole immersed in a uniformly magnetized force-free plasma. In the first part of this work, we present a family of stationary solutions that are jet-capable. While these solutions all satisfy the force-free equations and the appropriate boundary conditions, our numerical experiments show a unique relaxed state starting from different initial data, and so one member of the family is likely preferred over the others. In the second part of this work, we analyze the perturbations of this family of jet-like solutions, and show that the perturbative modes exhibit a similar split into the trapped and traveling categories previously found for perturbed Blandford-Znajek solutions. In the eikonal limit, the trapped modes can be identified with the fast magnetosonic waves in the force-free plasma and the traveling waves are essentially the Alfven waves. Moreover, within the scope of our analysis, we have not seen signs of unstable modes at the light-crossing timescale of the system, within which the numerical relaxation process occurs. This observation disfavors mode instability as the selection mechanism for picking out a preferred solution. Consequently, our analytical study is unable to definitively select a particular solution out of the family to serve as the aforementioned preferred final state. This remains an interesting open problem.