Epicyclic Oscillations of Fluid Bodies: Newtonian Nonslender Torus
Epicyclic Oscillations of Fluid Bodies: Newtonian Nonslender Torus
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流体的周转振荡：牛顿非细长环面
DOI：
10.1086/519782
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
U. Torkelsson
中科院分区：
文献类型：
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作者：
O. Blaes;E. Šrámková;M. Abramowicz;W. Kluźniak;U. Torkelsson
我们研究黑洞周围流体环面的周转振荡（在 Paczyński-Wiita 势中），并推导出其径向和垂直特征频率 νr 和 νz 的精确解析表达式，达到环面宽度的二阶精度。我们证明压力效应使特征频率小于自由粒子的特征频率。然而，当流体周转频率 νr 和 νz 比自由粒子对应的频率高约 15% 时，就会出现特定比率 νz/νr = 3/2，这对于高频准周期振荡 (QPO) 理论很重要。因此，我们的结果表明，之前对 QPO 黑洞自旋的估计产生了过高的值。
We study epicyclic oscillations of fluid tori around black holes (in the Paczyński-Wiita potential) and derive exact analytic expressions for their radial and vertical eigenfrequencies νr and νz to second-order accuracy in the width of the torus. We prove that pressure effects make the eigenfrequencies smaller than those for free particles. However, the particular ratio νz/νr = 3/2, which is important for the theory of high-frequency quasi-periodic oscillations (QPOs), occurs when the fluid tori epicyclic frequencies νr and νz are about 15% higher than the ones corresponding to free particles. Our results therefore suggest that previous estimates of black hole spins from QPOs have produced values that are too high.