Spectra from the Forming Region of the First Galaxies: The Effect of Aspherical Deceleration
Spectra from the Forming Region of the First Galaxies: The Effect of Aspherical Deceleration
复制标题
来自第一星系形成区域的光谱：非球面减速的影响
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
H. Kamaya
中科院分区：
文献类型：
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作者：
Masakazu A. R. Kobayashi;H. Kamaya
通过解决辐射传输问题来研究来自 Loeb-Rybicki (LR) 晕的 Lyα 线发射，该晕是第一星团周围膨胀的 H I 星际介质 (IGM) 和电离星际介质。虽然 Lyα 光子的初始散射光学深度约为 105，但当由于 H I IGM 膨胀导致的累积频移变得非常大时，大多数 Lyα 光子可以逃逸。当前的论文改进了先前对散射过程和 Lyα 传输不透明度的处理。为了证实 LR 晕的先前结果，我们研究了 IGM 的非球面扩张的影响。假设非球面性是在引力减速的初始阶段形成宇宙的大尺度丝状结构。根据我们的结果，非球面的影响使线轮廓的峰值波长移动到更长的波长，并且轮廓的半高宽变得比球面扩展模型的更宽。如果我们对大尺度结构的初始演化感兴趣，检测这些特征是有意义的，因为它们反映了当时 IGM 的动力学特性。此外，鉴于最近发现的高红移宇宙学再电离，我们简要评论了红移和宇宙学参数对线轮廓的影响。
Lyα line emission from the Loeb-Rybicki (LR) halo, which is the expanding H I intergalactic medium (IGM) around the first star clusters and the ionized interstellar medium, is investigated by solving a radiative transfer problem. While the initial scattering optical depth is ~105 for the Lyα photons, most of the Lyα photons can escape when the cumulative frequency-shift due to the expansion of the H I IGM becomes significantly large. The current paper improves on previous treatments of the scattering processes and the opacity for the Lyα transfer. Confirming the previous results of the LR halo, we investigate the effect of the aspherical expansion of the IGM. The asphericity is hypothesized to follow the initial stage of the gravitational deceleration to form the large-scale filamentary structure of the universe. According to our results, the effect of the asphericity lets the peak wavelength of the line profile shift to longer wavelengths and the FWHM of the profile become wider than those of the spherically expanding model. Detecting these features is meaningful if we are interested in the initial evolution of the large-scale structure, since they reflect the dynamical properties of the IGM at that time. Furthermore, given the recent discovery of the high-redshift cosmological reionization, we briefly comment on the effects of the redshift and the cosmological parameters on the line profile.