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首页> 外文期刊>PASJ: Publications of the Astronomical Society of Japan >Excitation of low-frequency QPOs in black-hole accretion flows
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Excitation of low-frequency QPOs in black-hole accretion flows

机译：激发黑洞积积流中的低频QPO

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We present the results of global three-dimensional magneto-hydrodynamic simulations of black-hole accretion flows. We focus on the dependence of the numerical results on the gas temperature supplied from the outer region. General-relativistic effects were taken into account using the pseudo-Newtonian potential. We ignored radiative cooling of the accreting gas. The initial state was a torus threaded by a weak azimuthal magnetic field. We found that the mass-accretion rate and the mass-outflow rate strongly depend on the temperature of the initial torus. The ratio of the average Maxwell stress generated by the magneto-rotational instability (MRI) to the gas pressure, alpha equivalent to < B omega B phi/4 pi >/< P >, is alpha similar to 0.05 in a hot torus and alpha similar to 0.01 in a cool torus. In the cool model, a constant angular momentum inner torus is formed around 4-8 r(s), where r(s) is the Schwarzschild radius. This inner torus deforms itself from a circle to a crescent quasi-periodically. During this deformation, the mass-accretion rate, the magnetic energy and the Maxwell stress increase. As the magnetic energy is released, the inner torus returns to a circular shape and starts the next cycle. The power spectral density (PSD) of the time variation of the mass-accretion rate in the cool model has a low-frequency peak around 10 Hz when we assumed a 10M(circle dot) black hole. The mass outflow rate in the low temperature model also shows quasi-periodic oscillation.
机译：我们介绍了黑洞积积流的全球三维磁流体动力学模拟的结果。我们关注数值结果对外部区域提供的气体温度的依赖性。使用伪牛顿势将广义相对论效应考虑在内。我们忽略了吸收气体的辐射冷却。初始状态是由弱方位角磁场穿过的圆环。我们发现质量增加率和质量流出率很大程度上取决于初始圆环的温度。磁旋转不稳定性（MRI）产生的平均麦克斯韦应力与气压的比值，α等于 /

，在热圆环中为0.05，而在α酷似圆环中的0.01。在酷模型中，恒定角动量内环面形成在4-8 r（s）左右，其中r（s）是Schwarzschild半径。该内部圆环将其自身从圆形变形为准周期性的月牙形。在这种变形过程中，质量增加率，磁能和麦克斯韦应力都会增加。随着磁能的释放，内环面恢复为圆形并开始下一个循环。当我们假设一个10M（圆点）黑洞时，冷模型中质量增加率的时间变化的功率谱密度（PSD）在10 Hz附近具有一个低频峰。低温模型中的质量流出率也显示出准周期振荡。

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