康普顿散射的Rosseland和通量平均不透明度
Rosseland and flux mean opacities for Compton scattering
摘要：
Rosseland平均不透明度在恒星演化理论和X射线暴模型中起着重要的作用。在高温状态下，当大部分气体完全电离时，康普顿散射主导了不透明度。在这里，我们的目标是严格评估以前的工作在这个问题上，并计算精确的Rosseland平均不透明度康普顿散射在很宽的温度范围和电子简并参数。我们使用相对论动力学方程的康普顿散射和计算光子的平均自由程作为光子能量的函数，通过求解相应的积分方程的扩散限制。作为一个副产品，我们还演示了如何计算光子再分布函数的情况下，简并电子。然后，我们计算Rosseland平均不透明度作为温度和电子简并度的函数。我们比较我们的结果与以前的计算，发现一个显着的差异，在低温制度和强简并。我们发现有用的解析表达式，以及近似的数值结果。然后，我们继续计算通量平均不透明度，并表明在扩散近似下，它几乎是相同的Rosseland平均不透明度。我们还提供了一个简单的方法来占的真实吸收的Rosseland和通量平均不透明度的评价。
英文摘要：
Rosseland mean opacity plays an important role in theories of stellar evolution and X-ray burst models. In the high-temperature regime, when most of the gas is completely ionized, the opacity is dominated by Compton scattering. Our aim here is to critically evaluate previous works on this subject and to compute exact Rosseland mean opacity for Compton scattering in a broad range of temperatures and electron degeneracy parameter. We use relativistic kinetic equations for Compton scattering and compute the photon mean free path as a function of photon energy by solving the corresponding integral equation in the diffusion limit. As a byproduct we also demonstrate the way to compute photon redistribution functions in case of degenerate electrons. We then compute the Rosseland mean opacity as a function of temperature and electron degeneracy. We compare our results to the previous calculations and find a significant difference in the low-temperature regime and strong degeneracy. We find useful analytical expressions that approximate well the numerical results. We then proceed to compute the flux mean opacity and show that in diffusion approximation it is nearly identical to the Rosseland mean opacity. We also provide a simple way for accounting for the true absorption in evaluation of the Rosseland and flux mean opacities.
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