AI 中文总结
研究红移\(z\simeq5.5\)的H\(α\)选定恒星形成星系样本的Ly\(α\)逃逸率，通过结合JWST成像与地面光谱数据，为探测Ly\(α\)逃逸建立通用框架，设定逃逸率上限，发现相关特性及环境影响。
AI 中文摘要
我们研究了红移\(z\simeq5.5\)的H\(α\)选定的恒星形成星系样本中的Ly\(α\)逃逸率（\(f_{\rm esc}\)），这些星系通过JWST/NIRCam F430M过剩识别，并由存档的VLT/MUSE数据覆盖。通过将内在Ly\(α\)产生与H\(α\)发射相关联，我们的方法为该时期恒星形成率\(\gtrsim 0.1\,M_\odot\,{\rm yr^{-1}}\)的星系中Ly\(α\)光子的逃逸提供了直接且无Ly\(α\)偏差的探测。在VLT/MUSE覆盖的12个星系中，有3个检测到Ly\(α\)发射。结合检测结果和上限，我们对总体平均Ly\(α\)逃逸率设定了保守上限\(\langle f_{\rm esc}^{\rm Ly\alpha} \rangle < 0.32\)。我们发现Ly\(α\)检测优先与几乎无尘埃的系统相关，而恒星形成率与\(f_{\rm esc}\)之间没有明显相关性，这表明Ly\(α\)逃逸是随机的。有趣的是，四个检测到Ly\(α\)的星系中有三个位于已知的过密结构内，这表明局部环境可能进一步促进Ly\(α\)光子的逃逸。我们的H\(α\)选定方法通过结合JWST中或窄带成像与地面光谱数据，建立了一个通用且可扩展的框架，用于探测Ly\(α\)逃逸，从而能够对再电离时代典型恒星形成星系中的Ly\(α\)可见性进行系统且偏差较小的研究。
英文摘要
We study the Ly$α$ escape fraction ($f_{\rm esc}$) in an H$α$-selected sample of star-forming galaxies at $z\simeq5.5$, identified via JWST/NIRCam F430M excess and covered by archival VLT/MUSE data. By anchoring the intrinsic Ly$α$ production to H$α$ emission, our approach provides a direct and Ly$α$-unbiased probe of the escape of Ly$α$ photons in galaxies with SFR $\gtrsim 0.1\,M_\odot\,{\rm yr^{-1}}$ at this epoch. Ly$α$ emission is detected in 3 out of 12 galaxies covered by VLT/MUSE. Combining detections and upper limits, we place a conservative upper bound of $\langle f_{\rm esc}^{\rm Lyα} \rangle < 0.32$ on the population-averaged Ly$α$ escape fraction. We find that Ly$α$ detections are preferentially associated with nearly dust-free systems, while no clear correlation between SFR and $f_{\rm esc}$, suggesting a stochastic picture of Ly$α$ escape. Interestingly, three of the four Ly$α$-detected galaxies reside within a known overdense structure, suggesting that local environment may further facilitate Ly$α$ photons escape. Our H$α$-selected approach establishes a general and scalable framework for probing Ly$α$ escape by combining JWST medium- or narrow-band imaging with ground-based spectroscopic data, enabling systematic and less biased studies of Ly$α$ visibility in typical star-forming galaxies during the post-reionization era.
Comments17 pages, 12 figures, ApJ accepted
