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arXiv 0801.3805gr-qcastro-ph
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旋转黑洞对引力平面波的散射和吸收

Scattering and absorption of gravitational plane waves by rotating black holes

Sam R. Dolan

摘要:

本文研究了真空中Kerr黑洞对平面引力波的散射和吸收。对于辐射沿旋转轴入射的特殊情况,我们采用分波法计算了截面。一个目录的数值精确的横截面,为一系列的入射波长$Mω\le 4$和旋转速率$a \le 0.999M$。详细研究了三种效应:偏振、螺旋反转和光散射。首先,一个新的近似的偏振在长波长的限制。我们表明,黑洞旋转区分同向和反向旋转波螺旋,导致一个长期的横截面成正比的$aω$。其次,我们确认螺旋度是不保守的散射过程中,并显示超辐射放大的效果。对于某些波长,对于快速旋转的空穴,反向散射通量被增强多达$\sim 35$倍(例如,对于$Mω= 0.945$处的$a = 0.999M$)。第三,我们观察到规则的荣耀和螺旋散射峰的数值确定的截面。我们表明,角宽度和强度的峰值可以估计通过一个半经典近似。最后,我们讨论了我们的结果的可观察到的影响。

英文摘要:

This is a study of the scattering and absorption of planar gravitational waves by a Kerr black hole in vacuum. We apply the partial wave method to compute cross sections for the special case of radiation incident along the rotation axis. A catalogue of numerically-accurate cross sections is presented, for a range of incident wavelengths $Mω\le 4$ and rotation rates $a \le 0.999M$. Three effects are studied in detail: polarization, helicity-reversal and glory scattering. First, a new approximation to the polarization in the long-wavelength limit is derived. We show that black hole rotation distinguishes between co- and counter-rotating wave helicities, leading to a term in the cross section proportional to $aω$. Second, we confirm that helicity is not conserved by the scattering process, and show that superradiance amplifies the effect. For certain wavelengths, the back-scattered flux is enhanced by as much as $\sim 35$ times for a rapidly-rotating hole (e.g. for $a = 0.999M$ at $Mω= 0.945$). Third, we observe regular glory and spiral scattering peaks in the numerically-determined cross sections. We show that the angular width and intensity of the peaks may be estimated via a semi-classical approximation. We conclude with a discussion of the observable implications of our results.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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