Black hole mergers: do gas discs lead to spin alignment?
Black hole mergers: do gas discs lead to spin alignment?
复制标题
黑洞合并：气盘会导致自旋排列吗？
DOI：
10.1093/mnrasl/sls018
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发表时间：
2012
影响因子：
4.8
通讯作者：
The University of Mississipi
中科院分区：
文献类型：
--
作者：
G. Lodato;D. P. D. D. Fisica;U. Milano;Milano;Italy.;D. Physics;Astronomy;The University of Mississipi
在这封信中，我们重新审视了Bardeen-Petterson效应可以共同排列中心超大质量黑洞双星自转的论点，该双星黑洞是从外双星(或外核盘)吸积而来的。我们通过增加对系统参数的依赖来改进先前的估计，并注意到在薄的粘性圆盘中翘曲传播的非线性性质影响对准。这降低了圆盘传递翘曲的能力，并可能严重降低圆盘辅助自旋对准的有效性。我们用随机失准和吸积率的蒙特卡罗实现来检验我们的预测，我们发现结果强烈地依赖于自旋幅度。我们通过作出自始至终都支持的假设，估计对齐的概率有一个慷慨的上限。即使有了这些假设，大约40%的0.5黑洞也没有时间对准圆盘。如果残余错位不小，并保持到最终的合并阶段，这可以给合并的空穴提供强大的反冲速度。因此，高速自转的黑洞更有可能受到强反冲的影响，而强反冲的发生目前还在争论中。
In this Letter, we revisit arguments suggesting that the Bardeen–Petterson effect can coalign the spins of a central supermassive black hole binary accreting from a circumbinary (or circumnuclear) gas disc. We improve on previous estimates by adding the dependence on system parameters and noting that the non-linear nature of warp propagation in a thin viscous disc affects alignment. This reduces the disc’s ability to communicate the warp, and can severely reduce the effectiveness of disc-assisted spin alignment. We test our predictions with a Monte Carlo realization of random misalignments and accretion rates, and we find that the outcome depends strongly on the spin magnitude. We estimate a generous upper limit to the probability of alignment by making assumptions which favour it throughout. Even with these assumptions, about 40 per cent of black holes with a 0.5 do not have time to align with the disc. If the residual misalignment is not small and it is maintained down to the final coalescence phase, this can give a powerful recoil velocity to the merged hole. Highly spinning black holes are thus more likely being subject to strong recoils, the occurrence of which is currently debated.