标题： 伽马射线暴环境中的线发射 显示英文标题

标题： Line emission from gamma-ray burst environments

摘要： 模拟了宇宙γ射线暴源周围的致密星环随时间和角度变化的谱线和连续辐射，考虑了光致电离、碰撞电离、复合以及电子由于各种过程而产生的加热和冷却。 强调了星环与膨胀激波之间的流体力学相互作用的重要性。 由于激波与致密星环相互作用时的快速减速，星环中的物质将被一种与低柱密度视线所观测到的截然不同的光子谱所照亮，并且会被激波与星环之间的流体力学相互作用加热。 提出了一种模型计算来再现GRB 970508 X射线余辉中观测到的铁K-α线发射。 结果显示，在小于10^{-4}个太阳质量的区域内，必须集中约10^{-3}秒差距范围内的铁。 激波与星环的流体力学相互作用导致了铁线的形成，这是主要的加热和电离机制。 这些结果表明，不对齐的伽马暴可能被探测为具有明显铁发射线特征的X射线闪。 显示英文摘要

摘要： The time and angle dependent line and continuum emission from a dense torus around a cosmological gamma-ray burst source is simulated, taking into account photoionization, collisional ionization, recombination, and electron heating and cooling due to various processes. The importance of the hydrodynamical interaction between the torus and the expanding blast wave is stressed. Due to the rapid deceleration of the blast wave as it interacts with the dense torus, the material in the torus will be illuminated by a drastically different photon spectrum than observable through a low-column-density line of sight, and will be heated by the hydrodynamical interaction between the blast wave and the torus. A model calculation to reproduce the Fe K-alpha line emission observed in the X-ray afterglow of GRB 970508 is presented. The results indicate that ~ 10^{-4} solar masses of iron must be concentrated in a region of less than 10^{-3} pc. The illumination of the torus material due to the hydrodynamic interaction of the blast wave with the torus is the dominant heating and ionization mechanism leading to the formation of the iron line. These results suggest that misaligned GRBs may be detectable as X-ray flashes with pronounced iron emission line features.