利用JWST莱曼-α分数测量探测再电离历史与电离泡尺度
Probing the Reionization History and Bubble Sizes with JWST Lyman-$α$ Fraction Measurements
- University of Pennsylvania（宾夕法尼亚大学）
- Northwestern University（西北大学）
机构由 AI 辅助整理，请以论文原文为准。
中文总结 AI 辅助
本研究利用JWST的Ly-α分数测量，结合THESAN模拟和半解析模型，约束再电离历史与电离泡尺寸，得出z~7-11处中性氢分数界限，验证了模型与观测的一致性。
中文摘要 AI 辅助
近期詹姆斯·韦布空间望远镜（JWST）的测量量化了在z~6-14处紫外选择的星系中可探测到莱曼-α（Ly-α）谱线的比例。这些Ly-α分数部分受周围星系间介质（IGM）中中性氢对Ly-α散射的影响，因此观测到的Ly-α分数演化可以增进我们对再电离历史以及再电离期间电离泡尺寸分布的理解。我们将JWST测量结果与基于THESAN再电离模拟和灵活的半解析模型的Ly-α透射计算进行比较。在每种情况下，我们利用z~6处Ly-α等效宽度（EW）分布的实测估计，校准一个用于宿主星系星际介质（ISM）和星系周介质（CGM）中产生的内禀Ly-α发射谱线的亚网格模型。我们发现THESAN中的再电离历史和电离泡尺寸与当前JWST Ly-α分数观测结果吻合良好，约化χ²ν=0.4-1.2。我们的半解析模型与THESAN Ly-α透射计算吻合良好，使我们能够探索广泛的再电离模型。我们推导出平均质量加权中性氢分数⟨xHI⟩的1σ界限：在z~7、8和11处，基于EW>25Å（>10Å）的Ly-α分数测量，分别为0.38^{+0.14}_{-0.38}（0.52^{+0.09}_{-0.21}）、0.57^{+0.23}_{-0.57}（0.68^{+0.12}_{-0.39}）和0.93^{+0.05}_{-0.17}（0.89^{+0.11}_{-0.15}）。
英文摘要
Recent James Webb Space Telescope (JWST) measurements quantify the fraction of ultraviolet-selected galaxies showing detectable Lyman-alpha (Ly-$α$) lines at $z \sim 6-14$. These Ly-$α$ fractions are partly shaped by Ly-$α$ scattering from neutral hydrogen in the surrounding intergalactic medium (IGM), and so the observed Ly-$α$ fraction evolution can inform our understanding of the reionization history and the size distribution of ionized bubbles during reionization. We compare the JWST measurements with Ly-$α$ transmission calculations based on both the THESAN reionization simulations and a flexible semi-analytic model. In each case, we calibrate a sub-grid model for the intrinsic Ly-$α$ emission lines emerging from the interstellar medium (ISM) and circumgalactic medium (CGM) of the host galaxies using empirical estimates of the Ly-$α$ equivalent width (EW) distributions at $z \sim 6$. We find that the reionization history and bubble sizes in THESAN yield good agreement with current JWST Ly-$α$ fraction observations, with a reduced $χ^2_ν= 0.4-1.2$. Our semi-analytic models and THESAN Ly-$α$ transmission calculations agree well, allowing us to explore a wide range of reionization models. We derive $1σ$ bounds on the average mass-weighted neutral fractions of: $\langle x_{\mathrm{HI}} \rangle$ = $0.38^{+0.14}_{-0.38}$ ($0.52^{+0.09}_{-0.21}$), $0.57^{+0.23}_{-0.57}$ ($0.68^{+0.12}_{-0.39}$), and $0.93^{+0.05}_{-0.17}$ ($0.89^{+0.11}_{-0.15}$) at $z \sim$ 7, 8, and 11, based on the Ly-$α$ fraction measurements with EW $>25\,\mathring{\rm A}$ ($>10\,\mathring{\rm A}$).
