绘制红移范围2.9<z<6.7内的莱曼-α逃逸分数及其对LAE再电离贡献的影响
Charting the Lyman-alpha escape fraction in the range 2.9<z<6.7 and consequences for the LAE reionisation contribution
AI总结：
本文通过研究A2744透镜星系团后方96个暗弱LAE及光度函数整体演化，揭示红移2.9至6.7范围内莱曼-α逃逸分数在暗端显著升高，z~6时接近100%，表明暗弱星系是宇宙再电离的重要贡献者。
摘要：
红移大于2时莱曼-α光子的逃逸是一个持续研究的课题，也是进一步理解莱曼-α发射体（LAEs）、莱曼-α光子穿过星际介质和星系际介质的传输，以及这些LAE对宇宙再电离影响的重要量。本研究旨在评估红移范围2.9<z<6.7内的莱曼-α逃逸分数，重点关注VLT/MUSE选定的、引力透镜放大后的、本质上暗弱的LAE。这些星系作为宇宙再电离的潜在驱动者尤其值得关注。我们通过两种方式评估莱曼-α逃逸分数：一是利用JWST/NIRCam和HST数据，对A2744透镜星系团后方96个LAE进行个体研究；二是利用最先进的LAE光度函数和经尘埃校正的紫外选定“母体”种群光度函数，研究逃逸分数的整体演化。我们将这些研究与文献中基于较亮样本的研究进行了比较。我们发现单个星系的逃逸分数随红移的演化可以忽略不计；这很可能被显著的固有弥散所掩盖。我们观察到随着紫外星等变暗，逃逸分数向更高值演化的趋势更为显著，并对这一关系进行了拟合。当比较两个光度函数以从整体意义上推导逃逸分数时，在将光度函数积分到亮端极限时，我们与先前文献的结果一致。然而，当使用与样本观测极限相当的暗端极限进行积分时，我们观察到逃逸分数值有所提高，尤其是在z~6附近，逃逸分数变得与100%一致。这表明在我们采样的暗弱区域中，趋向再电离时期的星系往往允许非常大比例的莱曼-α光子逃逸。（节略）
英文摘要：
The escape of Lyman-alpha photons at redshifts greater than two is an ongoing subject of study and an important quantity to further understanding of Lyman-alpha emitters (LAEs), the transmission of Lyman-alpha photons through the interstellar medium and intergalactic medium, and the impact these LAEs have on cosmic reionisation. This study aims to assess the Lyman-alpha escape fraction over the redshift range 2.9<z<6.7, focusing on VLT/MUSE-selected, gravitationally lensed, intrinsically faint LAEs. These galaxies are of particular interest as the potential drivers of cosmic reionisation. We assessed the Lyman-alpha escape fraction in two ways: through an individual study of 96 LAEs behind the A2744 lensing cluster, with JWST/NIRCam and HST data, and through a study of the global evolution of the escape fraction using the state-of-the-art luminosity functions for LAEs and the UV-selected `parent' population (dust-corrected). We compared these studies to those in the literature based on brighter samples. We find a negligible redshift evolution of the escape fraction for our individual galaxies; it is likely that it was washed out by significant intrinsic scatter. We observed a more significant evolution towards higher escape fractions with decreasing UV magnitude and fit this relation. When comparing the two luminosity functions to derive the escape fraction in a global sense, we saw agreement with previous literature when integrating the luminosity functions to a bright limit. However, when integrating using a faint limit equivalent to the observational limits of our samples, we observed enhanced escape fraction values, particularly around z~6, where the escape fraction becomes consistent with 100%. This indicates for the faint regimes we sampled that galaxies towards reionisation tend to allow very large fractions of Lyman-alpha photons to escape. (shortened)
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