标题： Lyman Alpha 辐射转移在多相介质中 显示英文标题

标题： Lyman Alpha Radiative Transfer in a Multi-Phase Medium

摘要： 氢Ly-alpha是我们研究高红移星系的主要发射线窗口。 令人惊讶的是，尽管已有大量文献，但在最现实的尘埃多相介质情况下，Ly-alpha辐射转移尚未受到详细的理论关注。 我们研究通过由尘埃、运动、光学厚气体云组成的集合体的共振散射。 我们将每个云团视为一个散射粒子，并使用表面散射的蒙特卡洛模拟来量化连续谱和Ly-alpha表面散射角度、吸收概率以及频率再分布，作为气体尘埃含量的函数。 这种原子化方法使模拟速度提高了多个数量级，使得原本难以计算的问题变得可行。 利用这些表面散射结果，我们开发了一个解析框架，用于估计逃逸分数和线宽作为气体几何结构、运动和尘埃含量的函数。 我们表明，关键的几何参数是在没有吸收的情况下逃逸的平均表面散射次数。 我们考虑了两个有趣的应用：(i) 等效宽度。 如果大部分尘埃位于冷中性云中，Ly-alpha可能优先从尘埃多相星际介质中逃逸，这可能解释了许多高红移/亚毫米源中观测到的异常高的等效宽度。 (ii) 多相星系风。 我们展示了特征轮廓是不对称的，具有宽阔的红色尾部，并将轮廓特征与风速和气体几何结构联系起来。 预计有许多未来应用。 [简写] 显示英文摘要

摘要： Hydrogen Ly-alpha is our primary emission-line window into high redshift galaxies. Surprisingly, despite an extensive literature, Ly-alpha radiative transfer in the most realistic case of a dusty, multi-phase medium has not received detailed theoretical attention. We investigate resonant scattering through an ensemble of dusty, moving, optically thick gas clumps. We treat each clump as a scattering particle and use Monte Carlo simulations of surface scattering to quantify continuum and Ly-alpha surface scattering angles, absorption probabilities, and frequency redistribution, as a function of the gas dust content. This atomistic approach speeds up the simulations by many orders of magnitude, making possible calculations which are otherwise intractable. With these surface scattering results, we develop an analytic framework for estimating escape fractions and line widths as a function of gas geometry, motion, and dust content. We show that the key geometric parameter is the average number of surface scatters for escape in the absence of absorption. We consider two interesting applications: (i) Equivalent widths. Ly-alpha can preferentially escape from a dusty multi-phase ISM if most of the dust lies in cold neutral clouds, possibly explaining anomalously high EWs seen in many high redshift/submm sources. (ii) Multi-phase galactic outflows. We show the characteristic profile is asymmetric with a broad red tail, and relate the profile features to the outflow speed and gas geometry. Many future applications are envisaged. [Abridged]