Rotating black holes in Einstein-aether theory
Rotating black holes in Einstein-aether theory
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DOI：
10.1088/1361-6382/ac5053
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发表时间：
2021-07
影响因子：
3.5
通讯作者：
Alexander Adam;P. Figueras;T. Jacobson;T. Wiseman
中科院分区：
文献类型：
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作者：
Alexander Adam;P. Figueras;T. Jacobson;T. Wiseman
本文首次在爱因斯坦-以太理论中引入了新的方法来数值构造稳态轴对称黑洞解，并研究了它们的性质。关键的技术挑战是在自旋2、1和0波模式视界上施加规则性。有趣的是，我们发现度制视界和各种波模式视界都不是杀戮视界，它们有零发生器，没有杀戮向量的线性组合相切，从极点到赤道螺旋，反之亦然。现有的现象学约束导致了两个耦合参数区域，其中理论可行且某些耦合较大；区域I有一个大的扭转联轴器，区域II也有一个（有点）大的膨胀联轴器。目前，这些限制还不包括来自强场动力学的测试，比如对黑洞及其合并的观察。考虑到大以太耦合，人们可能会期望这样的动力学明显偏离广义相对论（GR），从而进一步限制该理论。在这里，我们认为情况并非如此，因为对于这些参数区域，存在解决方案，其中以太被“绘制”到与GR非常接近的度量背景上。区域I的绘制近似独立于大扭曲耦合，区域II也近似独立于大膨胀耦合，并垂直于时空的最大叶理。我们对弱场进行了解析支持，对旋转黑洞的解进行了数值支持，它们与克尔度规非常接近。
We introduce new methods to numerically construct for the first time stationary axisymmetric black hole solutions in Einstein-aether theory and study their properties. The key technical challenge is to impose regularity at the spin-2, 1, and 0 wave mode horizons. Interestingly we find the metric horizon, and various wave mode horizons, are not Killing horizons, having null generators to which no linear combination of Killing vectors is tangent, and which spiral from pole to equator or vice versa. Existing phenomenological constraints result in two regions of coupling parameters where the theory is viable and some couplings are large; region I with a large twist coupling and region II with also a (somewhat) large expansion coupling. Currently these constraints do not include tests from strong field dynamics, such as observations of black holes and their mergers. Given the large aether coupling(s) one might expect such dynamics to deviate significantly from general relativity (GR), and hence to further constrain the theory. Here we argue this is not the case, since for these parameter regions solutions exist where the aether is ‘painted’ onto a metric background that is very close to that of GR. This painting for region I is approximately independent of the large twist coupling, and for region II is also approximately independent of the large expansion coupling and normal to a maximal foliation of the spacetime. We support this picture analytically for weak fields, and numerically for rotating black hole solutions, which closely approximate the Kerr metric.