标题： 黑洞吸积流数值模拟中的拟周期振荡 显示英文标题

标题： Quasi-Periodic Oscillations in Numerical Simulation of Accretion Flows Around Black Holes

摘要： 我们展示了使用光滑粒子流体动力学（SPH）方法对围绕黑洞的二维轴对称吸积流进行的若干数值模拟结果。我们同时考虑了恒星级黑洞和超大质量黑洞。我们假设辐射复合（bremsstrahlung）是唯一的冷却源，因为它在数值模拟中更容易实现。 我们观察到由于吸积流中冲击波的径向和垂直振荡，内盘的光度和平均热能含量表现出非常有趣的行为。当功率密度谱被测量时，在恒星级黑洞的情况下，可以看到几赫兹以及偶尔数百赫兹的准周期振荡。 对于超大质量黑洞，振荡的时间尺度范围从数小时到数周。功率密度谱具有通常的平坦顶部行为，平均 {\it 均方根} 幅度为百分之几，并且呈现分段幂律行为。断点频率通常接近黑洞观测功率谱中看到的拟周期振荡（QPO）频率。 显示英文摘要

摘要： We present results of several numerical simulations of two dimensional axi-symmetric accretion flows around black holes using the Smoothed Particle Hydrodynamics (SPH). We consider both stellar black holes and as well as super-massive black holes. We assume bremsstrahlung to be the only source of cooling as it is simpler to implement in numerical simulations. We observe that due to both radial and vertical oscillation of shock waves in the accretion flow, the luminosity and average thermal energy content of the inner disk exhibit very interesting behaviors. When power density spectra are taken, quasi-periodic oscillations are seen at a few Hz and also occasionally at hundreds of Hz for stellar black holes. For super-massive black holes, the time-scale of the oscillations ranges from hours to weeks. The power density spectra have usual flat top behavior with average {\it rms} amplitude a few percent and a broken power-law behavior. The break frequency is generally found to be close to the QPO frequency as seen in the observed power spectra of black holes.