Title: Extended Lyman-$α$ emission towards the SPT2349-56 protocluster at $z=4.3$ Show Chinese title

Title: 向SPT2349-56原星系团延伸的Lyman-$α$发射在$z=4.3$

Abstract: Context. Deep spectroscopic surveys with the Atacama Large Millimeter/submillimeter Array (ALMA) have revealed that some of the brightest infrared sources in the sky correspond to concentrations of dusty star-forming galaxies (DSFG) at high redshift. Among these, the SPT2349-56 protocluster system at z = 4.304 is amongst the most extreme examples due to its high source density and integrated star formation rate. Aims. We conducted a deep Lyman-$\alpha$ line emission survey around SPT2349-56 using the Multi-Unit Spectroscopic Explorer (MUSE) at Very Large Telescope (VLT) in order to characterize this uniquely dense environment. Methods. Taking advantage of the deep three-dimensional nature of this survey, we performed a sensitive search for Lyman-$\alpha$ emitters (LAEs) toward the core and northern extension of the protocluster, which correspond to the brightest infrared regions in this field. Using a smoothed narrowband image extracted from the MUSE datacube around the protocluster redshift, we searched for possible extended structures. Results. We identify only three LAEs at z = 4.3 in this field, in concordance with expectations for blank-fields, and an extended Lyman-$\alpha$ structure spatially associated with core of the protocluster. All the previously-identified DSFGs in this field are undetected in Lyman-$\alpha$ emission, consistent with the conspicuous dust obscuration in these systems. We find an extended Lyman-$\alpha$ structure, about $60 \times 60$ kpc$^{2}$ in size, and located 56 kpc west of the protocluster core. Three DSFGs coincide spatially with the location of this structure. We conclude that either the three co-spatial DSFGs or the protocluster core itself are feeding ionizing photons to the Lyman-$\alpha$ structure. Show Chinese abstract

Abstract: 上下文。 使用阿塔卡马大型毫米波/亚毫米波阵列（ALMA）的深光谱调查表明，天空中最明亮的红外源中的一些对应于高红移处尘埃丰富的星系形成星系（DSFG）的集中区域。 其中，红移为4.304的SPT2349-56原星系团系统是这些例子中最极端的一个，因为其源密度高且整体恒星形成率高。 目的。 我们利用在甚大望远镜（VLT）上的多单元光谱探测器（MUSE）对SPT2349-56周围的Lyman-$\alpha$线发射进行了深度调查，以表征这个独特密集的环境。 方法。 利用这次调查的深度三维特性，我们对原星系团的核心和北部延伸区域进行了对Lyman-$\alpha$发射体（LAEs）的灵敏搜索，这些区域对应于该场中最明亮的红外区域。 通过从MUSE数据立方体中提取的平滑窄带图像，在原星系团红移附近进行搜索，寻找可能的扩展结构。 结果。 我们在该场中仅识别出三个红移为4.3的LAEs，这与空白场的预期一致，并发现一个与原星系团核心空间相关的扩展Lyman-$\alpha$结构。 该场中所有之前识别的DSFGs在Lyman-$\alpha$发射中均未被检测到，这与这些系统中明显的尘埃遮蔽一致。 我们发现了一个扩展的Lyman-$\alpha$结构，大小约为$60 \times 60$ kpc$^{2}$，位于原星系团核心以西56 kpc处。 三个DSFGs在空间上与该结构的位置重合。 我们得出结论，要么三个共面的DSFGs，要么原星系团核心本身正在向莱曼-$\alpha$结构提供电离光子。