利用JELS-MUSE限制再电离时期的Lyα逃逸：z~6.1处一个高完整性的Hα选样
Constraining reionization-era Ly$α$ escape with JELS-MUSE: a highly complete H$α$-selected sample at $z\sim6.1$
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中文总结 AI 辅助
该研究利用JELS-MUSE对z≈6.1的24个恒星形成星系开展观测，测得Lyα逃逸分数，发现其散射源于ISM而非IGM，相关结果为再电离末期的Lyα逃逸提供了基准。
中文摘要 AI 辅助
Lyα逃逸分数f_{esc}^{Lyα}既探测控制电离光子逃逸的星际介质（ISM）条件，也探测再电离时期（EoR）期间星系际介质（IGM）中性分数的上升。在IGM衰减占主导之前，表征由ISM驱动的f_{esc}^{Lyα}的本征分布，对于解释观测到的Lyα在EoR期间可见性的下降至关重要。我们呈现了24个z≈6.1的恒星形成星系的f_{esc}^{Lyα}测量值，这些星系是从JWST发射线巡天（JELS）中选出的高完整性、Hα流量限样本，作为JELS-MUSE大天区巡天的一部分，利用甚大望远镜（VLT）的多单元光谱探测器（MUSE）对Lyα进行观测。我们在24个源中的12个中探测到Lyα，且根据经典的等效宽度（Lyα）>25埃的定义，Lyα发射体占比X_{Lyα}=33±12%。通过反向Kaplan-Meier生存分析纳入未探测源后，得到平均f_{esc}^{Lyα}=0.07^{+0.04}_{-0.03}，与独立堆叠流量估计值0.08^{+0.02}_{-0.02}一致。利用与我们巡天的天区、深度和红移范围匹配的再电离模拟，我们发现所有星系预计经历大致相似的IGM透射，因此我们假设f_{esc}^{Lyα}的大散射反映了由ISM驱动的真实方差，而非周围IGM的差异。在探测到的源中，更高f_{esc}^{Lyα}的星系往往具有更低的星云尘埃衰减、更蓝的紫外斜率和更低的恒星质量，这与通过恒星形成区域周围局部低柱密度ISM通道实现的反馈调控逃逸一致。这些结果为再电离末期的本征Lyα逃逸提供了基准，可用于解释z>7处的IGM抑制效应。
英文摘要
The Ly$α$ escape fraction, $f_{\rm{esc}}^{\rm{Ly}α}$, probes both the interstellar medium (ISM) conditions governing ionizing photon escape and the rising neutral fraction of the IGM through the Epoch of Reionization (EoR). Characterising the intrinsic, ISM-driven distribution of $f_{\rm{esc}}^{\rm{Ly}α}$ before IGM attenuation becomes dominant is essential to interpret the observed decline in Ly$α$ visibility through the EoR. We present $f_{\rm{esc}}^{\rm{Ly}α}$ measurements for a highly complete, H$α$-flux-limited sample of 24 star-forming galaxies at $z \approx 6.1$, drawn from the JWST Emission Line Survey (JELS) and observed in Ly$α$ with VLT/MUSE as part of the JELS-MUSE Large Area Survey. We detect Ly$α$ in 12 of 24 sources and a Ly$α$ emitter fraction of $X_{\rm{Ly}α} = 33 \pm 12$ per cent using the canonical EW(Ly$α$) $> 25 \, \mathring{\rm{A}}$ definition. Incorporating non-detections via reverse Kaplan-Meier survival analysis yields $\langle f_{\rm{esc}}^{\rm{Ly}α} \rangle = 0.07^{+0.04}_{-0.03}$, consistent with an independent stacked-flux estimate of $0.08^{+0.02}_{-0.02}$. Using reionization simulations matched to the area, depth, and redshift range of our survey, we find that all galaxies are expected to experience broadly similar IGM transmission, so we postulate that the large scatter in $f_{\rm{esc}}^{\rm{Ly}α}$ reflects genuine ISM-driven variance rather than differences in the surrounding IGM. Among the detections, higher $f_{\rm{esc}}^{\rm{Ly}α}$ galaxies tend to have lower nebular dust attenuation, bluer UV slopes, and lower stellar mass, consistent with feedback-regulated escape through localised, low-column-density ISM channels around star-forming regions. These results benchmark intrinsic Ly$α$ escape at the end of reionization, against which IGM suppression at $z > 7$ can be interpreted.
发表机构
- University of Edinburgh（爱丁堡大学）
- Durham University（杜伦大学）
- Armagh Observatory and Planetarium（阿马天文台和行星馆）
- Instituto de Física y Astronomía（物理与天文学研究所）
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