构建低红移（z < 0.4）莱曼α发射体的氢线库：利用SPHEREx估算尘埃消光并评估帕邢线的可探测性
Constructing a Hydrogen Line Library for Lyα Emitters at Low Redshifts (z < 0.4): Estimating Dust Extinction and Assessing Paschen line Detectability with SPHEREx
AI总结：
本研究构建低红移（z < 0.4）莱曼α发射体的氢线库，估算部分星系尘埃消光，优化14个星系的消光曲线，并评估SPHEREx研究氢发射线选星系的可行性。
AI中文摘要：
氢复合线是恒星形成星系最强的发射线之一，可作为恒星形成率和电离光子产生率的指示器，用于探测早期宇宙。不同复合线的比值除了能提供H II区物理诊断的线索外，还可用于估算尘埃消光。为了为未来针对不同红移氢线的近红外光谱巡天和光学窄带成像巡天做准备，我们通过汇编已发表文献中的数据构建了氢复合线库。我们的汇编包含260个星系，其中大部分位于z < 0.4，且至少观测到一条氢复合线。所研究的具体氢发射线包括三条巴尔末线（Hα、Hβ和Hγ）以及莱曼α线。在被汇编的星系中，我们对85个至少探测到两条巴尔末线的星系，通过假设Case B复合机制和Calzetti消光曲线来估算其尘埃消光，并在此基础上推断莱曼α逃逸分数。对于所有三条巴尔末线均被探测到的14个星系，我们对消光曲线进行优化，使其在三种可能的巴尔末线比值下产生一致的E(B-V)值，结果显示尘埃消光曲线的斜率存在多样性。我们还通过对星系样本的帕邢线进行建模，评估了利用未来如SPHEREx这类光谱巡天研究氢发射线选星系的可行性。
英文摘要：
Hydrogen recombination lines, one of the strongest emission lines from star-forming galaxies, are used to probe the early Universe as indicators of star formation rates and ionizing photon production rates. Ratios between different recombination lines provide clues to estimate dust attenuation, in addition to the H II region physical diagnostics. To prepare for future near-infrared spectral surveys and optical narrow-band imaging surveys aiming for hydrogen lines in different redshifts, we construct hydrogen recombination line libraries by compiling data from published literature. Our compilation includes 260 galaxies mostly at z < 0.4, of which at least one hydrogen recombination line is observed. The specific hydrogen emission lines under investigation encompass three Balmer lines (Hα, H\b{eta} and Hγ) and Lyα line. Of the compiled galaxies, we estimated dust extinction for 85 galaxies that have detections of at least two Balmer lines, by assuming the Case B recombination and Calzetti extinction curve, based on which Lyα escape fraction is also inferred. For each of the 14 galaxies with detections of all three Balmer lines, we optimized the extinction curve so that it yields consistent E(B-V) values across the three possible Balmer line ratios, showing the variety in the slope of the dust attenuation curve. We further evaluated the feasibility of studying hydrogen emission line-selected galaxies with future spectral surveys such as SPHEREx by modeling the Paschen lines of our galaxy sample.
