论文标题
在电离III结束时，得克萨斯州光谱搜索$α$排放。 $α$等效宽度分布和电离结构$ z> 7 $
Texas Spectroscopic Search for Ly$α$ Emission at the End of Reionization III. the Ly$α$ Equivalent-width Distribution and Ionized Structures at $z > 7$
论文作者
论文摘要
可以利用来自星系的Ly $α$发射来表征播层间介质（IGM）中的电离状态。我们报告了使用全面的Keck/Mosfire近红外光谱数据集对$ Z> 7 $的搜索，这是德克萨斯州光谱搜索在Reionization调查结束时对LY $α$排放的一部分。我们分析了10晚的Mosfire观测值的数据，这些数据共同针对了Goods-N Field中的72个高$ Z $候选星系，全部曝光时间为4.5-19 HR。利用改进的自动排放线搜索，我们报告了在$ z> 7 $下检测到的10章$α$排放线（$> $ 4 $σ$），从而大大增加了光谱确认的样本。我们的样本包括大型等效宽度（ew）ly $α$发射器（$> $50Å），以及从五个附加星系中检测到的额外的暂定LY $α$发射线。我们将LY $α$ ew分布限制为$ z \ sim7.6 $，发现从$ z \ lyssim6 $下降了，这表明在此时期，IgM中的中性氢（HI）越来越多。我们通过IGM估计LY $α$传输（$ = $ ew $ _ {z \ sim \ sim \ text {7.6}} $/ew $ _ {z \ sim \ sim \ sim \ sim \ sim \ text {2-6}} $），并推断igm hi fraction（$ x _ _ {$ x _ {\ fext {\ hi Hi} $） $ 49^{+19} _ { - 19} \％$ at $ z \ sim7.6 $，在$ z \ sim $ 7.6的最新尺寸中，较小的张力（$> $ 1 $σ$）较低。检测到的$α$发射器的空间分布意味着存在$ z \ sim7.55 $的潜在高度电离区域，该区域在$ 40 cmpc的空间分离中载有四个ly $α$ emitters。尽管我们的分析也对所选的参考ly $α$ ew分布值和重离模型敏感，但我们数据集中这个电离区域的突出性可以解释我们的$ x _ {\ text {hi}} $的低推断值。
Ly$α$ emission from galaxies can be utilized to characterize the ionization state in the intergalactic medium (IGM). We report our search for Ly$α$ emission at $z>7$ using a comprehensive Keck/MOSFIRE near-infrared spectroscopic dataset, as part of the Texas Spectroscopic Search for Ly$α$ Emission at the End of Reionization Survey. We analyze data from 10 nights of MOSFIRE observations which together target 72 high-$z$ candidate galaxies in the GOODS-N field, all with deep exposure times of 4.5-19 hr. Utilizing an improved automated emission-line search, we report 10 Ly$α$ emission lines detected ($>$4$σ$) at $z>7$, significantly increasing the spectroscopically confirmed sample. Our sample includes large equivalent-width (EW) Ly$α$ emitters ($>$50Å), and additional tentative Ly$α$ emission lines detected at 3 - 4$σ$ from five additional galaxies. We constrain the Ly$α$ EW distribution at $z\sim7.6$, finding a significant drop from $z\lesssim6$, suggesting an increasing fraction of neutral hydrogen (HI) in the IGM in this epoch. We estimate the Ly$α$ transmission through the IGM ($=$EW$_{z\sim\text{7.6}}$/EW$_{z\sim\text{2-6}}$), and infer an IGM HI fraction ($X_{\text{HI}}$) of $49^{+19}_{-19}\%$ at $z\sim7.6$, which is lower in modest tension ($>$1$σ$) with recent measurements at $z \sim$ 7.6. The spatial distribution of the detected Ly$α$ emitters implies the presence of a potential highly ionized region at $z\sim7.55$ which hosts four Ly$α$ emitters within a $\sim$ 40 cMpc spatial separation. The prominence of this ionized region in our dataset could explain our lower inferred value of $X_{\text{HI}}$, though our analysis is also sensitive to the chosen reference Ly$α$ EW distribution values and reionization models.
