Monte Carlo simulations of global Compton cooling in inner regions of hot accretion flows
Monte Carlo simulations of global Compton cooling in inner regions of hot accretion flows
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热吸积流内部区域整体康普顿冷却的蒙特卡洛模拟
DOI：
10.1111/j.1365-2966.2009.16135.x
复制
发表时间：
2009-09
影响因子：
4.8
通讯作者：
Xie, Fu-Guo
中科院分区：
文献类型：
--
作者：
Niedzwiecki, Andrzej;Yuan, Feng;Zdziarski, Andrzej A.;Xie, Fu-Guo
热吸积流，如以平流为主的吸积流，在径向上通常是光学薄的。因此，在某些半径上产生的光子可以通过康普顿散射冷却或加热其他半径上的电子。这种全球性的康普顿散射先前已被证明对吸积流的动力学很重要。在这里，我们通过使用精确的全局广义相对论蒙特卡洛模拟来扩展先前对这个问题的处理。我们关注吸积流的内部区域（R < 600R(g)），得到了该区域的全局自洽解。与不自溶的初始溶液相比，最终溶液的冷却速率和电子温度在大于或接近10R(g)的半径处均显著降低。另一方面，自相容溶液的辐射光谱具有与初始迭代相似的形状，除了高能截止点的能量降低了约2倍，热光度降低了约2倍。我们还比较了全局康普顿散射模型与球形和平板几何的局部模型。我们发现平板模型比球形模型更接近全局模型。尽管如此，两种局部模型都不能很好地近似于冷却速率的径向分布，而且差异可能高达两个数量级。局部板坯模型低估了外部区域的冷却速率，而高估了内部区域的冷却速率。我们将我们的模型结果与观测到的黑洞双星的硬态光谱进行了比较，发现在任何盘流出都很弱的情况下，两者的总体一致性很好。我们发现，广义相对论效应在动力学被全局复合化修正的流动中是接近这一一致性的关键。
Hot accretion flows such as advection-dominated accretion flows are generally optically thin in the radial direction. Thus, photons generated at some radii can cool or heat electrons at other radii via Compton scattering. Such global Compton scattering has previously been shown to be important for the dynamics of accretion flows. Here, we extend previous treatments of this problem by using accurate global general relativistic Monte Carlo simulations. We focus on an inner region of the accretion flow (R < 600R(g)), for which we obtain a global self-consistent solution. As compared to the initial, not self-consistent solution, the final solution has both the cooling rate and the electron temperature significantly reduced at radii of greater than or similar to 10R(g). On the other hand, the radiation spectrum of the self-consistent solution has a shape similar to that of the initial iteration, except for the high-energy cut-off being at an energy lower by a factor of similar to 2 and the bolometric luminosity decreased by a factor of similar to 2. We also compare the global Compton scattering model with local models in spherical and slab geometries. We find that the slab model approximates the global model significantly better than the spherical one. Still, neither local model gives a good approximation to the radial profile of the cooling rate, and the differences can be up to two orders of magnitude. The local slab model underestimates the cooling rate at outer regions whereas it overestimates that rate at inner regions. We compare our modelling results to observed hard-state spectra of black hole binaries and find an overall good agreement provided any disc outflow is weak. We find that general relativistic effects in flows whose dynamics is modified by global Comptonization is crucial in approaching this agreement.
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DOI：
10.1086/533512
发表时间：
2008-03
期刊：
The Astrophysical Journal
影响因子：
--
作者：
A. Joinet;E. Kalemci;F. Senziani;F. Senziani;F. Senziani
通讯作者：
A. Joinet;E. Kalemci;F. Senziani;F. Senziani;F. Senziani
DOI：
10.1111/j.1365-2966.2010.17092.x
发表时间：
2009-11
影响因子：
4.8
作者：
C. Done;M. D. Trigo
通讯作者：
C. Done;M. D. Trigo
DOI：
10.1111/j.1365-2966.2005.09752.x
发表时间：
2005-07
影响因子：
4.8
作者：
A. Niedźwiecki;A. Zdziarski
通讯作者：
A. Niedźwiecki;A. Zdziarski
DOI：
10.1086/508644
发表时间：
2006-02
期刊：
The Astrophysical Journal
影响因子：
--
作者：
J. Miller;J. Homan;D. Steeghs;M. Rupen;R. Hunstead;R. Wijnands;P. Charles;A. Fabian
通讯作者：
J. Miller;J. Homan;D. Steeghs;M. Rupen;R. Hunstead;R. Wijnands;P. Charles;A. Fabian
DOI：
10.1086/342402
发表时间：
2002-10
期刊：
The Astrophysical Journal
影响因子：
--
作者：
A. Zdziarski;J. Poutanen;W. Paciesas;L. Wen
通讯作者：
A. Zdziarski;J. Poutanen;W. Paciesas;L. Wen