We use state of the art hydrodyamical simulations from the Sherwood, EAGLE and Illustris projects to examine the signature of $M_{\rm z=0}\simeq 10^{14}M_{\odot}$ protoclusters observed in Ly-$α$ absorption at $z\simeq 2.4$. We find there is a weak correlation between the mass overdensity, $δ_{\rm m}$, and the Ly-$α$ effective optical depth relative to the mean, $δ_{τ_\textrm{eff}}$, averaged over $15~h^{-1}\rm\,cMpc$ scales, although scatter in the $δ_{\rm m}$--$δ_{τ_\textrm{eff}}$ plane means it is not possible to uniquely identify large scale overdensities with strong Ly-$α$ absorption. Although all protoclusters are associated with large scale mass overdensities, most sight lines through protoclusters in a $\sim 10^{6}$ $\rm cMpc^{3}$ volume probe the low column density Ly-$α$ forest. A small subset of sight lines that pass through protoclusters exhibit coherent, strong Ly-$α$ absorption on $15h^{-1}\rm\,cMpc$ scales, although these correspond to a wide range in mass overdensity. Assuming perfect removal of contamination by Ly-$α$ absorbers with damping wings, more than half of the remaining sight lines with $δ_{τ_{\rm eff}}>3.5$ trace protoclusters. It is furthermore possible to identify a model dependent $δ_{τ_{\rm eff}}$ threshold that selects only protoclusters. However, such regions are rare: excluding absorption caused by damped systems, less than 0.1 per cent of sight lines that pass through a protocluster have $δ_{τ_{\rm eff}}>3.5$, meaning that any protocluster sample selected in this manner will also be highly incomplete. On the other hand, coherent regions of Ly-$α$ absorption also provide a promising route for identifying and studying filamentary environments at high redshift.
TARDIS Paper II: Synergistic Density Reconstruction from Lyman-alpha Forest and Spectroscopic Galaxy Surveys with Applications to Protoclusters and the Cosmic Web
Galaxy Protoclusters as Drivers of Cosmic Reionization: I. Bubble Overlap at Redshift z ~ 7 in LAGER-z7OD1
University of California Santa Barbara（加州大学圣塔芭芭拉分校）；Goddard Space Flight Center（戈达德太空飞行中心）；The University of Tokyo（东京大学）；Space Telescope Science Institute（太空望远镜科学研究所）；MIT Kavli Institute for Astrophysics and Space Research（麻省理工学院卡弗里天体物理学与空间研究研究所）；CNRS, Institut d'Astrophysique de Paris（法国国家科学研究中心，巴黎天体物理研究所）；Chinese Academy of Sciences（中国科学院）；University of Science and Technology of China（中国科学技术大学）
The birth of the intracluster medium: the evolution of multiphase gas and Lyman-$α$ haloes in a simulated $z\sim3$ protocluster
University of Nottingham（诺丁汉大学）；The University of Texas at Dallas（德克萨斯大学达拉斯分校）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）；University of Cambridge（剑桥大学）
The youth of the intracluster medium. I. A non-parametric characterisation of the gas and electron number density profiles of $z \simeq 2$ protoclusters
Università di Bologna（博洛尼亚大学）；Istituto di Radioastronomia, INAF（意大利国家天体物理研究所射电天文研究所）；Universitäts-Sternwarte, Fakultät für Physik, Ludwig-Maximilians-Universität München（慕尼黑大学天体物理系）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）；INAF - IASF Milano（意大利国家天体物理研究所米兰天体物理研究所）；INAF-Osservatorio Astrofisico di Arcetri（意大利国家天体物理研究所阿切特里天文台）；Université Paris-Saclay（巴黎萨克雷大学）；Université Paris Cité（巴黎西岱大学）
Stellar Masses of Lyman Break Galaxies, Lyman Alpha Emitters and Radio Galaxies in Overdense Regions at z=4-6
我们提出了新的信息，星系附近的发光射电星系和类星体在z= 4，5，6。这些领域以前被发现包含超密度的莱曼Break Galerkin（LBG）或光谱莱曼α发射体。我们使用HST和斯皮策数据来推断恒星质量，并将我们的结果与大天文台起源深度调查（GOODS）探测的更平均环境中的大样本LBG进行对比。获得了以下结果。首先，在z=4-5处的过密区域和场中的LBG在z '-[3.6]与[3.6]的色星等图中处于非常相似的序列上。这被解释为恒星质量的序列（log[M*/Msun] = 9-11），其中星系由于尘埃和年龄而变得越来越红，因为它们的恒星形成率（SFR）增加。第二，这两个射电星系是已知存在于z~4-5的最大质量天体（log[M*/Msun]~11）之一，并且根据25倍大面积GOODS调查估计的此类天体的低数量密度，它们是极其罕见的。我们认为，这些大质量星系和超大质量黑洞的存在是通过气体的快速吸积或在过密区域内的合并而增强的。第三，根据与z=1.2的大质量X射线星团Cl 1252的比较，在z=4的“原星团”TN 1338中发现的总恒星质量占<30% of the stellar mass on the cluster red sequence expected to have formed at z>4。虽然未来的近红外观测应该可以确定目前是否有任何大质量星系被遗漏，但这种质量差异的一…
