Title: Photometric IGM tomography with Subaru/HSC: the large-scale structure of Ly$α$ emitters and IGM transmission in the COSMOS field at $z\sim5$ Show Chinese title

Title: 使用 Subaru/HSC 的光度 IGM 断层扫描：COSMOS 星域中 Ly$α$发射体的大尺度结构和$z\sim5$的 IGM 传输

Abstract: We present a novel technique called "photometric IGM tomography" to map the intergalactic medium (IGM) at $z\simeq4.9$ in the COSMOS field. It utilizes deep narrow-band (NB) imaging to photometrically detect faint Ly$\alpha$ forest transmission in background galaxies across the Subaru/Hyper-Suprime Cam (HSC)'s $1.8\rm\,sq.\,deg$ field of view and locate Ly$\alpha$ emitters (LAEs) in the same cosmic volume. Using ultra-deep HSC images and Bayesian spectral energy distribution fitting, we measure the Ly$\alpha$ forest transmission at $z\simeq4.9$ along a large number ($140$) of background galaxies selected from the DEIMOS10k spectroscopic catalogue at $4.98<z<5.89$ and the SILVERRUSH LAEs at $z\simeq5.7$. We photometrically measure the mean Ly$\alpha$ forest transmission and achieve a result consistent with previous measurements based on quasar spectra. We also measure the angular LAE-Ly$\alpha$ forest cross-correlation and Ly$\alpha$ forest auto-correlation functions and place an observational constraint on the large-scale fluctuations of the IGM around LAEs at $z\simeq4.9$. Finally, we present the reconstructed 2D tomographic map of the IGM, co-spatial with the large-scale structure of LAEs, at a transverse resolution of $11 \,h^{-1}\rm cMpc$ across $140\,h^{-1}\rm cMpc$ in the COSMOS field at $z\simeq4.9$. We discuss the observational requirements and the potential applications of this new technique for understanding the sources of reionization, quasar radiative history, and galaxy-IGM correlations across $z\sim3-6$. Our results represent the first proof-of-concept of photometric IGM tomography, offering a new route to examining early galaxy evolution in the context of the large-scale cosmic web from the epoch of reionization to cosmic noon. Show Chinese abstract

Abstract: 我们提出了一种名为“光度学际星系介质断层扫描”的新技术，用于绘制COSMOS区域中$z\simeq4.9$的际星系介质（IGM）图。 它利用深窄带（NB）成像来光度学检测背景星系中 Subaru/广域巡天相机（HSC）$1.8\rm\,sq.\,deg$视野内微弱的Ly$\alpha$森林透射，并在同一宇宙体积内定位Ly$\alpha$发射体（LAE）。 利用超深的 HSC 图像和贝叶斯谱能分布拟合方法，我们测量了大量（$140$）来自 DEIMOS10k 光谱目录中红移为$4.98<z<5.89$的背景星系以及红移为$z\simeq5.7$的 SILVERRUSH 电离氢区发射线星系的沿视线方向（$z\simeq4.9$）的 Ly$\alpha$森林透射率。 我们通过测光法测量了平均 Ly$\alpha$森林透射率，并得到了与基于类星体光谱的先前测量一致的结果。 我们还测量了角度 LAE-Ly$\alpha$森林交叉关联函数和 Ly$\alpha$森林自相关函数，并对 LAE 周围 IGM 的大尺度涨落进行了观测限制，范围为$z\simeq4.9$。 最后，我们在 COSMOS 星场中以横跨$140\,h^{-1}\rm cMpc$范围内的横向分辨率为$11 \,h^{-1}\rm cMpc$重建了与 LAE 大尺度结构共空间的 IGM 的二维断层图，时间范围为$z\simeq4.9$。 我们讨论了这种新技术在理解再电离源、类星体辐射历史以及星系-IGM 相关性方面的观测需求和潜在应用，跨越$z\sim3-6$。 我们的结果代表了光度 IGM 断层扫描的第一个概念验证，提供了一种新的途径，可以在从再电离时代到宇宙正午的大尺度宇宙网络背景下研究早期星系的演化。