标题： 在COSMOS区域识别红移$\sim$ 4.5的原星系团形成：Taralay原星系团的扩展，由围绕亚毫米星系的Ly-alpha发射体追踪 显示英文标题

标题： Identifying a protocluster formation at z $\sim$ 4.5 in the COSMOS field: an extension of Taralay protocluster, traced by Ly-alpha emitters surrounding a submm galaxy

摘要： 我们报告在COSMOS场中发现了一个包含多个高密度区的大尺度结构，位于$z= 4.54 \pm 0.03$处，其中最显著的一个可能正在向最近发现的Taralay原星系团坠落。 我们使用组合宽波段和窄波段光学测光法，在距离亚毫米源J1000+0234 21 cMpc范围内识别出Ly$\alpha$发射体（LAEs），在$z= 4.54$处识别出可能描绘潜在结构的典型恒星形成星系。 我们的方法将线发射体选为窄波段过量物体，并利用COSMOS2020测光红移目录来排除可能的低红移干扰者，它们的线发射（例如，[OIII]在$z\sim 0.3$处）可能是窄波段中观测到过量的原因。 与场区的LAE密度相比，我们的结果表明在区域$\bar\delta = 3$内存在一个平均LAE数量的过密度，该区域为$27 \times 20 \times 36$ cMpc$^3$，可能演变成中等质量的星系团（$3 - 10 \times 10^{14} \, M_\odot$）在$z\sim 0$。 这项工作支持这样一个观点，即亚毫米波源虽然偏离主要过密度峰值，但作为中等质量、可能正在落入的结构的痕迹。 显示英文摘要

摘要： We report the discovery of a large-scale structure containing multiple overdensities at $z= 4.54 \pm 0.03$ in the COSMOS field, with the most prominent one likely infalling towards the recently identified Taralay protocluster. We use combined wide-band and narrow-band optical photometry to identify Ly$\alpha$ emitters (LAEs) within a 21 cMpc radius from the submm source J1000+0234, at $z= 4.54$, to identify typical star-forming galaxies that may trace an underlying structure. Our approach selects line emitters as narrow-band excess objects and we use the COSMOS2020 photometric redshift catalog to eliminate potential low-redshift interlopers whose line emission (e.g. [OIII] at $z\sim 0.3$) might be responsible for the observed excess in the narrow band. In comparison with the LAE density in the field, our results point to a mean LAE number overdensity of $\bar\delta = 3$ spanning a region of $27 \times 20 \times 36$ cMpc$^3$, probably evolving into a moderate-mass cluster ($3 - 10 \times 10^{14} \, M_\odot$) at $z\sim 0$. This work supports the idea that submm sources, although offset from the major overdensity peaks, serve as traces of moderately massive, potentially infalling structures.