A simple framework for modelling the dependence of bulk Comptonization by turbulence on accretion disc parameters
A simple framework for modelling the dependence of bulk Comptonization by turbulence on accretion disc parameters
复制标题
用于模拟湍流体积康普顿化对吸积盘参数的依赖性的简单框架
DOI：
10.1093/mnras/sty540
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发表时间：
2018
影响因子：
4.8
通讯作者：
S. Hirose
中科院分区：
文献类型：
--
作者：
J. Kaufman;O. Blaes;S. Hirose
活动星系核中软X射线过剩的温压实化模型不能自洽地解释压实化介质和底层吸积盘之间的关系。正因为如此，他们不能直接将拟合的康普顿化温度和光学厚度与吸积盘参数联系起来。由于在高辐射压力主导的圆盘中，整体速度超过热速度，在这些系统中，湍流的整体压实化可以为温压实化模型提供圆盘本身的物理基础。我们模拟了体积康普顿化与基本吸积盘参数的关系，如质量、光度、半径、自旋、内边界条件和α。除了约束热康普顿化模型外，我们的模型还可以帮助区分体康普顿化对软X射线过剩的贡献与其他物理机制的贡献，如吸收和反射。通过将体压实化的时间变异性与磁旋转不稳定(MRI)湍流引起的盘垂直结构的波动联系起来，我们的结果表明，对软X射线过剩的观测可以用来研究辐射压强主导区域的盘湍流。由于我们的模型以一种物理直观的方式将整体康普顿化与一维垂直结构的温度分布联系在一起，这将有助于在未来的模拟中理解这种影响。
Warm Comptonization models for the soft X-ray excess in AGN do not self-consistently explain the relationship between the Comptonizing medium and the underlying accretion disc. Because of this, they cannot directly connect the fitted Comptonization temperatures and optical depths to accretion disc parameters. Since bulk velocities exceed thermal velocities in highly radiation pressure dominated discs, in these systems bulk Comptonization by turbulence may provide a physical basis in the disc itself for warm Comptonization models. We model the dependence of bulk Comptonization on fundamental accretion disc parameters, such as mass, luminosity, radius, spin, inner boundary condition, and $\alpha$. In addition to constraining warm Comptonization models, our model can help distinguish contributions from bulk Comptonization to the soft X-ray excess from those due to other physical mechanisms, such as absorption and reflection. By linking the time variability of bulk Comptonization to fluctuations in the disc vertical structure due to magnetorotational instability (MRI) turbulence, our results show that observations of the soft X-ray excess can be used to study disc turbulence in the radiation pressure dominated regime. Because our model connects bulk Comptonization to one dimensional vertical structure temperature profiles in a physically intuitive way, it will be useful for understanding this effect in future simulations run in new regimes.