非常光学厚的星周盘中的辐射转移
Radiative transfer in very optically thick circumstellar disks
摘要：
本文提出了两种有效的扩散近似实现方法，用于大质量星周盘尘埃介质中辐射转移的蒙特卡罗计算。其目的是提高计算温度结构的准确性，并减少计算时间。在参数空间的各个角落的方法的精度，效率和适用性进行了研究。使用这些方法对从流体静力平衡计算得到的拱星盘的垂直结构的影响也得到了解决。提出了两种方法。首先，使用能量扩散近似来提高盘的高度模糊区域中的温度结构的准确性，其中光子计数低。第二，采用改进的随机游走近似，以减少计算时间。这种修改后的随机游走确保了最终在高密度区域的光子可以快速逃逸到低密度区域，而这些光子在磁盘中沉积的能量仍然可以精确计算。一个新的辐射转移的代码，MCMax，在这两个扩散近似实施。这些可以同时用于提高计算速度和减少统计噪声。我们的结论是，扩散近似允许快速和准确的计算的温度结构，垂直盘结构和可观的非常光学厚的星周盘。
英文摘要：
In this paper we present two efficient implementations of the diffusion approximation to be employed in Monte Carlo computations of radiative transfer in dusty media of massive circumstellar disks. The aim is to improve the accuracy of the computed temperature structure and to decrease the computation time. The accuracy, efficiency and applicability of the methods in various corners of parameter space are investigated. The effects of using these methods on the vertical structure of the circumstellar disk as obtained from hydrostatic equilibrium computations are also addressed. Two methods are presented. First, an energy diffusion approximation is used to improve the accuracy of the temperature structure in highly obscured regions of the disk, where photon counts are low. Second, a modified random walk approximation is employed to decrease the computation time. This modified random walk ensures that the photons that end up in the high-density regions can quickly escape to the lower density regions, while the energy deposited by these photons in the disk is still computed accurately. A new radiative transfer code, MCMax, is presented in which both these diffusion approximations are implemented. These can be used simultaneously to increase both computational speed and decrease statistical noise. We conclude that the diffusion approximations allow for fast and accurate computations of the temperature structure, vertical disk structure and observables of very optically thick circumstellar disks.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
