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arXiv 0903.3684gr-qc
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大质量Kerr黑洞的椭圆末稳定轨道研究

A Study of Elliptical Last Stable Orbits About a Massive Kerr Black Hole

P. G. Komorowski, S. R. Valluri, M. Houde

摘要:

在进行轨道演化数值分析时,最后稳定轨道是一个重要的边界条件。虽然对于实验粒子围绕史瓦西黑洞(SBH)的椭圆轨道和围绕标准化自旋为S(|J| /M^2,其中J是KBH的自旋角动量)的克尔黑洞(KBH)的圆形轨道的情况,已经很好地理解了LSO;但是值得将我们的知识扩展到包括围绕KBH的椭圆轨道。这一扩展有助于为更好地理解引力波(GW)发射奠定基础。在这项工作中描述的数学发展源于使用一个有效的潜力(V)来自克尔度规,它封装了伦瑟-瑟林岁差。这使我们能够开发一种新的形式的解析表达式来计算任意KBH自旋的圆形轨道(R_LSO)的LSO半径。然后,我们能够构建一个数值方法来计算椭圆LSO的直肠侧(l_LSO)。关于E^2(归一化轨道能量的平方)和L^2(归一化轨道角动量的平方)的偏心率e和纵距l的公式,以前曾由其他人针对SBH周围的椭圆轨道提出,然后扩展到KBH的情况;我们利用这些结果将我们的解析l_LSO方程推广到椭圆轨道。从我们的分析方程和数值程序计算的LSO数据,和以前出版的,然后进行比较,发现是非常一致的。

英文摘要:

The last stable orbit (LSO) of a compact object (CO) is an important boundary condition when performing numerical analysis of orbit evolution. Although the LSO is already well understood for the case where a test-particle is in an elliptical orbit around a Schwarzschild black hole (SBH) and for the case of a circular orbit about a Kerr black hole (KBH) of normalised spin, S (|J|/M^2, where J is the spin angular momentum of the KBH); it is worthwhile to extend our knowledge to include elliptical orbits about a KBH. This extension helps to lay the foundation for a better understanding of gravitational wave (GW) emission. The mathematical developments described in this work sprang from the use of an effective potential (V) derived from the Kerr metric, which encapsulates the Lense-Thirring precession. That allowed us to develop a new form of analytical expression to calculate the LSO Radius for circular orbits (R_LSO) of arbitrary KBH spin. We were then able to construct a numerical method to calculate the latus rectum (l_LSO) for an elliptical LSO. Abstract Formulae for E^2 (square of normalised orbital energy) and L^2 (square of normalised orbital angular momentum) in terms of eccentricity, e, and latus rectum, l, were previously developed by others for elliptical orbits around an SBH and then extended to the KBH case; we used these results to generalise our analytical l_LSO equations to elliptical orbits. LSO data calculated from our analytical equations and numerical procedures, and those previously published, are then compared and found to be in excellent agreement.

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