CHORUS. IV. Mapping the Spatially Inhomogeneous Cosmic Reionization with Subaru HSC
CHORUS. IV. Mapping the Spatially Inhomogeneous Cosmic Reionization with Subaru HSC
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DOI：
10.3847/1538-4357/ac4b5d
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发表时间：
2022-01
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通讯作者：
T. Yoshioka;N. Kashikawa;A. Inoue;Satoshi Yamanaka;K. Shimasaku;Y. Harikane;T. Shibuya;R. Momose-R.-Momos
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文献类型：
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作者：
T. Yoshioka;N. Kashikawa;A. Inoue;Satoshi Yamanaka;K. Shimasaku;Y. Harikane;T. Shibuya;R. Momose-R.-Momos
空间不均匀性是理解再电离过程的重要特征之一；然而，它尚未被完全量化。为了绘制这种不均匀分布图，我们从 Subaru/Hyper Suprime-Cam 大面积（∼1.5 deg2 = 34,000 cMpc2）深度勘测中同时检测 z ∼ 6.6 处的 Lyα 发射器（LAE）和莱曼断裂星系（LBG）。我们使用数值辐射传输模拟，根据观测到的 LAE 与 LBG 的数密度比 n(LAE)/n(LBG) 来估计中性分数 x HI，其中选择模型星系以满足观测到的选择函数。虽然视场内的平均 x HI 被发现为 x HI < 0.4，这与之前的研究一致，但发现每 140 pMpc2 区域的视场内 n(LAE)/n(LBG) 的变化高达 3 倍。这可能表明再电离的空间不均匀拓扑，但也留下了这种变化基于星系分布的固有大尺度结构的可能性。根据模拟，从当前的调查中可能很难区分两者。我们还发现，在高 EW0 时，高 LAE 密度区域中的 LAE 数量更多，这支持了观察到的 n(LAE)/n(LBG) 或多或少由中性分数驱动的事实，尽管统计显着性不高。
Spatial inhomogeneity is one of the important features for understanding the reionization process; however, it has not yet been fully quantified. To map this inhomogeneous distribution, we simultaneously detect Lyα emitters (LAEs) and Lyman-break galaxies (LBGs) at z ∼ 6.6 from the Subaru/Hyper Suprime-Cam large-area (∼1.5 deg2 = 34,000 cMpc2) deep survey. We estimate the neutral fraction, x HI, from the observed number density ratio of LAEs to LBGs, n(LAE)/n(LBG), using numerical radiative transfer simulations, in which model galaxies are selected to satisfy the observed selection function. While the average x HI within the field of view is found to be x HI < 0.4, which is consistent with previous studies, the variation of n(LAE)/n(LBG) within the field of view for every 140 pMpc2 area is found to be as large as a factor of 3. This may suggest a spatially inhomogeneous topology of reionization, but it also leaves open the possibility that the variation is based on the inherent large-scale structure of the galaxy distribution. Based on the simulations, it may be difficult to distinguish between the two from the current survey. We also find that LAEs in the high-LAE-density region are more numerous at high EW0, supporting the fact that the observed n(LAE)/n(LBG) is more or less driven by the neutral fraction, though the statistical significance is not high.