论文标题
Blandford - 重新审视的Znajek Monopole扩展:对功率排放的新颖非分析贡献
Blandford--Znajek monopole expansion revisited: novel non-analytic contributions to the power emission
论文作者
论文摘要
Blandford和Znajek(BZ)拆分单键杆是该机制的重要理论例子,该机制可以驱动从Kerr黑洞中驱动能量的电磁。它被构造为无力电动力学(FFE)的扰动低自旋溶液。最近,Armas $ et〜$ $通过清除明显的不同渐近学问题来使这座建筑更加坚定。这是通过解决外面光表面周围的行为(FFE方程的临界表面)来实现的。在此基础上,我们重新审视BZ扰动扩展,并将扰动方法扩展到Kerr黑洞的旋转参数中的更高阶。我们采用匹配的反应扩张和半分析技术来将裂单键溶液扩展到扰动理论中的第六阶。扩展必然包括自旋参数中的新对数贡献。我们表明,这些高阶项会导致对功率和角动量输出的非分析贡献。特别是,我们首次计算自旋参数中第七和第八阶的能量提取的扰动贡献。能量提取的结果公式可改善有限自旋时数值模拟的一致性。此外,我们提出了一种新的数值程序,用于解决外部光线表面上的FFE方程,从而导致收敛速度明显更快,并将其扩展到更高的阶。最后,我们将光表面作为FFE方程的关键表面进行了一般讨论。
The Blandford and Znajek (BZ) split-monopole serves as an important theoretical example of the mechanism that can drive the electromagnetic extraction of energy from Kerr black holes. It is constructed as a perturbative low spin solution of Force Free Electrodynamics (FFE). Recently, Armas $et~al.$ put this construction on a firmer footing by clearing up issues with apparent divergent asymptotics. This was accomplished by resolving the behavior around the outer light surface, a critical surface of the FFE equations. Building on this, we revisit the BZ perturbative expansion, and extend the perturbative approach to higher orders in the spin parameter of the Kerr black hole. We employ matched-asymptotic-expansions and semi-analytic techniques to extend the split-monopole solution to the sixth-order in perturbation theory. The expansion necessarily includes novel logarithmic contributions in the spin parameter. We show that these higher order terms result in non-analytic contributions to the power and angular momentum output. In particular, we compute for the first time the perturbative contributions to the energy extraction at seventh- and eighth-order in the spin parameter. The resulting formula for the energy extraction improves the agreement with numerical simulations at finite spin. Moreover, we present a novel numerical procedure for resolving the FFE equations across the outer light surface, resulting in significantly faster convergence and greater accuracy, and extend this to higher orders as well. Finally, we include a general discussion of light surfaces as critical surfaces of the FFE equations.