在恒星形成星系中发现z≈7.57处的莱曼-α森林：对宇宙再电离时间和拓扑结构的启示
Discovery of the Lyman-$α$ Forest in a Star-Forming Galaxy at $z \approx 7.57$: Implications for the Timing and Topology of Cosmic Reionization
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中文总结 AI 辅助
利用JWST在z≈7.57恒星形成星系中显著探测到莱曼-α森林，表明存在异常透明的IGM视线，暗示大质量星系可能对宇宙再电离有更大贡献。
中文摘要 AI 辅助
再电离纪元期间星系电离光子逃逸通常是通过间接方式推断的，因为在这些红移处，星系际介质（IGM）中的中性氢预计会吸收莱曼-α蓝侧的所有通量。然而，在本工作中，我们利用JWST/NIRSpec PRISM光谱在z≈7.57处的大质量（M*≈10^9.1 M☉）恒星形成星系JADES-GS-z7-LAF中显著探测到（≈7σ）Lyα蓝侧通量。我们利用JWST/NIRCam F090W成像（≈10σ）独立确认了莱曼-α森林（LAF）的这一探测。F090W中的蓝侧通量与星系在空间上重合，并在λ_rest≈1500 Å处从其紫外质心约0.4 pkpc处出现。我们没有发现前景干扰源产生观测通量的证据，尽管现有数据无法正式排除这种解释。透射通量意味着在z≈5.5-7.5处穿过IGM的一条异常透明的视线（x_HI≪0.1%），该视线在空间和运动学上与众多高红移星系过密区域重合，这可能解释了该通量的出现。我们观察到Lyα断裂附近平滑且渐进的转折，这要么与极端阻尼翼（N_HI≈10^23.3 cm^-2）一致，要么与强星云连续谱（在λ_rest=1500 Å处贡献约60-70%的通量）一致。JADES-GS-z7-LAF比通常被认为是宇宙再电离驱动源的暗弱源要明亮得多（M_UV≈-21.5，与GN-z11相似）。如果此类系统在早期宇宙中普遍存在，那么大质量星系对电离光子预算的贡献可能超过其他间接约束所暗示的水平。
英文摘要
The escape of ionizing photons from galaxies during the Epoch of Reionization is often inferred indirectly because the intervening neutral hydrogen in the intergalactic medium (IGM) is expected to absorb all flux blueward of Lyman-$α$ at these redshifts. However, in this work, we report the significant detection ($\approx7σ$) of flux blueward of Ly$α$ in a massive ($M_{\ast}\approx10^{9.1}\ M_{\odot}$) star-forming galaxy at $z\approx7.57$, JADES-GS-z7-LAF, using JWST/NIRSpec PRISM spectroscopy. We independently confirm this detection of the Ly$α$ forest (LAF) using JWST/NIRCam F090W imaging ($\approx10σ$). The blueward flux in F090W is spatially coincident with the galaxy and emerges $\approx0.4$ pkpc from its UV centroid at $λ_{\mathrm{rest}}\approx1500\ \mathrm{\mathring{A}}$. We find no evidence for a foreground interloper producing the observed flux, although we cannot formally reject this interpretation with the existing data. The transmitted flux implies an extraordinarily transparent sightline ($x_{\mathrm{HI}}\ll0.1\%$) through the IGM at $z \approx 5.5-7.5$, a sightline that is spatially and kinematically coincident with numerous high-redshift galaxy overdensities, which possibly explains the emergence of this flux. We observe a smooth and gradual turnover around the Ly$α$ break that is either consistent with an extreme damping-wing ($N_{\mathrm{HI}}\approx10^{23.3}\ \mathrm{cm}^{-2}$) or a strong nebular continuum (contributing $\approx60-70\%$ of the flux at $λ_{\mathrm{rest}}=1500\ \mathrm{\mathring{A}}$). JADES-GS-z7-LAF is far more luminous ($M_{\mathrm{UV}}\approx-21.5$, similar to GN-z11) than the faint sources usually invoked as the drivers of cosmic reionization. If such systems are common in the early Universe, massive galaxies may contribute more to the ionizing photon budget than suggested by other indirect constraints.
发表机构
- The Pennsylvania State University（宾夕法尼亚州立大学）
- University of Copenhagen（哥本哈根大学）
- University of Arizona（亚利桑那大学）
机构由 AI 辅助整理，请以论文原文为准。
