论文标题
幂律密度曲线中的谐振线辐射转移
Resonant-line radiative transfer within power-law density profiles
论文作者
论文摘要
星系中的恒星形成区域周围被大量的气体储藏，能够发出和吸收Lyman-Alpha（Lya）辐射。对Lya发射器和空间扩展的Lya光环的观察确实为星系的形成和演变提供了见解。但是，由于谐振散射的复杂性，文献中只有少数分析解决方案。我们讨论了几种理想化但有力动机的情景，以将现有的形式主义扩展到新的分析解决方案，从而实现了有关LYA光子的运输和扩散的定量预测。这包括用于辐射场和衍生数量的封闭形式解决方案，包括新兴通量，峰位置，能量密度，平均内部光谱，散射数，外部力乘数，捕获时间和特征性半径。为了验证我们的预测，我们采用了强大的无网状蒙特卡洛辐射转移（GMCRT）方法，该方法可以直接将其纳入现有的射线追踪代码中，但需要对基于不透明度的计算进行修改，包括动态核心技巧的加速方案。我们主要关注幂律密度和发射率曲线，但是分析方法和数值方法都可以推广到其他情况。这样的研究提供了有关物理环境和整个宇宙星系的观察性特征之间联系的额外直觉和理解。
Star-forming regions in galaxies are surrounded by vast reservoirs of gas capable of both emitting and absorbing Lyman-alpha (Lya) radiation. Observations of Lya emitters and spatially extended Lya haloes indeed provide insights into the formation and evolution of galaxies. However, due to the complexity of resonant scattering, only a few analytic solutions are known in the literature. We discuss several idealized but physically motivated scenarios to extend the existing formalism to new analytic solutions, enabling quantitative predictions about the transport and diffusion of Lya photons. This includes a closed form solution for the radiation field and derived quantities including the emergent flux, peak locations, energy density, average internal spectrum, number of scatters, outward force multiplier, trapping time, and characteristic radius. To verify our predictions, we employ a robust gridless Monte Carlo radiative transfer (GMCRT) method, which is straightforward to incorporate into existing ray-tracing codes but requires modifications to opacity-based calculations, including dynamical core-skipping acceleration schemes. We primarily focus on power-law density and emissivity profiles, however both the analytic and numerical methods can be generalized to other cases. Such studies provide additional intuition and understanding regarding the connection between the physical environments and observational signatures of galaxies throughout the Universe.
