Lyman α emitters in ionized bubbles: constraining the environment and ionized fraction
Lyman α emitters in ionized bubbles: constraining the environment and ionized fraction
复制标题
电离气泡中的莱曼α发射器：约束环境和电离分数
DOI：
10.1093/mnras/stad2228
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发表时间：
2023
影响因子：
4.8
通讯作者：
Davies, Frederick B.
中科院分区：
文献类型：
--
作者：
Trapp, A. C.;Furlanetto, Steven R.;Davies, Frederick B.
莱曼α发射器(LAE)是再电离过程的优秀探测器，因为它们必须被大的电离气泡包围，才能在再电离时代可见。大的电离区被认为对应于过密集的区域，可能是原始星系团，这使它们成为早期大质量结构的有趣试验台。含有几个LAE的紧密缔合通常被认为是过密的电离气泡的标志。在这里，我们开发了第一个框架来量化高z星系缔合的电离场和密度场。我们探讨了(I)测量场的大尺度密度，(Ii)由于高红移(z∼7)亮源的小数目密度而产生的泊松噪声和(Iii)电离分数对LAE观测的影响之间的相互作用。我们使用贝叶斯统计、一个简单的再电离模型和蒙特卡罗模拟，构建了一种比以往工作更全面的计算LAE区大尺度密度的方法。我们发现泊松噪声对一个区域的推断密度有很大的影响，并说明了如何推断电离分数。然后，我们将我们的框架应用于迄今确定的最强关联：胡等人。在∼7的宇宙场中发现了体积为50 000cMpc3的14个LaE。我们表明，这很可能是一个电离或接近电离的气泡内部的2.4cMpc超密度。我们还表明，这种LAE关联意味着，在简单的再电离模型的背景下，全局电离分数是。
Lyman α emitters (LAEs) are excellent probes of the reionization process, as they must be surrounded by large ionized bubbles in order to be visible during the reionization era. Large ionized regions are thought to correspond to overdense regions and may be protoclusters, making them interesting test-beds for early massive structures. Close associations containing several LAEs are often assumed to mark overdense, ionized bubbles. Here, we develop the first framework to quantify the ionization and density fields of high-zgalaxy associations. We explore the interplay between (i) the large-scale density of a survey field, (ii) Poisson noise due to the small number density of bright sources at high redshifts (z∼ 7), and (iii) the effects of the ionized fraction on the observation of LAEs. We use Bayesian statistics, a simple model of reionization, and a Monte Carlo simulation to construct a more comprehensive method for calculating the large-scale density of LAE regions than previous works. We find that Poisson noise has a strong effect on the inferred density of a region and show how the ionized fraction can be inferred. We then apply our framework to the strongest association yet identified: Hu et al. found 14 LAEs in a volume of ∼50 000 cMpc3inside the COSMOS field atz∼ 7. We show that this is most likely a 2.4σ overdensity inside of an ionized or nearly ionized bubble. We also show that this LAE association implies that the global ionized fraction is, within the context of a simple reionization model.