Three-dimensional structure of clumpy outflow from supercritical accretion flow onto black holes
Three-dimensional structure of clumpy outflow from supercritical accretion flow onto black holes
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DOI：
10.1093/pasj/psx157
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发表时间：
2018-02
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影响因子：
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通讯作者：
H. Kobayashi;K. Ohsuga;H. R. Takahashi;T. Kawashima;Y. Asahina;S. Takeuchi;S. Mineshige
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作者：
H. Kobayashi;K. Ohsuga;H. R. Takahashi;T. Kawashima;Y. Asahina;S. Takeuchi;S. Mineshige
我们对 10 Msun 黑洞周围超临界吸积流的流出进行了全局三维 (3D) 辐射流体动力学 (RHD) 模拟。我们只求解流出部分，从接近稳态的轴对称二维模拟数据开始，但在方位角方向添加正弦形式的小扰动。在基础 2D 模拟数据中，黑洞的质量吸积率为 ~10^2 L_E/c^2，流出率为 ~10 L_E/c^2（LE 和 c 分别是爱丁顿光度和光速）。我们首先确认了在距中心黑洞数百史瓦西半径 (r_S) 的光球层上方出现了块状流出物，这是通过 2D RHD 模拟发现的。作为突出的 3D 特征，我们发现这些团块具有撕裂片的形状，而不是切割的绳子，并且它们以亚开普勒速度围绕中心黑洞旋转，距离中心约 10^3 r_S。典型的团块尺寸在径向方向上约为 30 r_S 或更小，并且在角度方向上更拉长，最多约为数百 r_S。纸张分离范围为 50 至 150 r_S。当团块穿过远处观察者的视线时，我们预计会出现随机的时间变化。对于质量为十到几十米太阳的黑洞，变化时间尺度估计为几秒，与一些超亮X射线源的观测结果大致一致。
We perform global three-dimensional (3D) radiation-hydrodynamic (RHD) simulations of out- flow from supercritical accretion flow around a 10 Msun black hole. We only solve the outflow part, starting from the axisymmetric 2D simulation data in a nearly steady state but with small perturbations in a sinusoidal form being added in the azimuthal direction. The mass accretion rate onto the black hole is ~10^2 L_E/c^2 in the underlying 2D simulation data and the outflow rate is ~10 L_E/c^2 (with LE and c being the Eddington luminosity and speed of light, respectively). We first confirm the emergence of clumpy outflow, which was discovered by the 2D RHD simulations, above the photosphere located at a few hundreds of Schwarzschild radii (r_S) from the central black hole. As prominent 3D features we find that the clumps have the shape of a torn sheet, rather than a cut string, and that they are rotating around the central black hole with a sub-Keplerian velocity at a distance of ~10^3 r_S from the center. The typical clump size is ~30 r_S or less in the radial direction, and is more elongated in the angular directions, ~hundreds of r_S at most. The sheet separation ranges from 50 to 150 r_S. We expect stochastic time variations when clumps pass across the line of the sight of a distant observer. Variation timescales are estimated to be several seconds for a black hole with mass of ten to several tens of Msun, in rough agreement with the observations of some ultra-luminous X-ray sources.