标题： 利用Lyman-$α$透射尖峰限制再电离的尾端 显示英文标题

标题： Constraining the Tail-End of Reionization Using Lyman-$α$ Transmission Spikes

摘要： 我们研究了合成类星体光谱中Lyman-$\alpha$传输尖峰在$z > 5$处的特性，并讨论了它们与星系际介质属性之间的联系及其限制再电离模型的能力。 我们使用来自“计算机上的宇宙再电离”系列的最先进的辐射流体动力学模拟来预测传输尖峰的数量随红移的变化，既考虑了无限光谱分辨率的理想情况，也考虑了现实观测环境。 传输尖峰出现在位于紫外光源附近的高电离稀疏区域。 我们发现，大多数预测的尖峰目前的观测无法解析，且表明我们的模拟光谱在大约15%的实现中与类星体ULAS J1120+0641的观测结果一致。 尖峰高度与气体密度和电离分数均呈相关性，但当合成光谱被平滑到实际可达到的光谱分辨率时，前者的关系被消除。 尖峰宽度与相关稀疏区域的范围存在线性关系，其斜率随红移变化。 与观测结果一致，在明亮星系附近的小范围内传输通量受到抑制，因为这些星系位于过密区域。 我们认为，这种反相关性可以用来限制大尺度密度模式。 显示英文摘要

摘要： We investigate Lyman-$\alpha$ transmission spikes at $z > 5$ in synthetic quasar spectra, and discuss their connection to the properties of the intergalactic medium and their ability to constrain reionization models. We use state-of-the-art radiation-hydrodynamic simulations from the Cosmic Reionization On Computers series to predict the number of transmission spikes as a function of redshift, both in the ideal case of infinite spectral resolution and in a realistic observational setting. Transmission spikes are produced in highly-ionized underdense regions located in the vicinity of UV sources. We find that most of the predicted spikes are unresolved by current observations, and show that our mock spectra are consistent with observations of the quasar ULAS J1120+0641 in about 15% of the realizations. The spike height correlates with both the gas density and the ionized fraction, but the former link is erased when synthetic spectra are smoothed to realistically achievable spectral resolutions. There exists a linear relationship between spike width and the extent of the associated underdense region, with a slope that is redshift-dependent. In agreement with observations, the spike transmitted flux is suppressed at small distance from bright galaxies as these reside in overdense regions. We argue that this anti-correlation can be used to constrain large-scale density modes.