Understanding the structure of the matter distribution in the Universe due to the action of the gravitational instability -- the cosmic web -- is complicated by lack of direct analytic access to the nonlinear domain of structure formation. Here, we suggest and apply a novel tessellation method designed for cold dark matter (CDM) N-body cosmological simulations. The method is based on the fact that the initial CDM state can be described by a 3-D manifold (in a 6-D phase space) that remains continuous under evolution. Our technique uses the full phase space information and has no free parameters; it can be used to compute multi-stream and density fields, the main focus of this paper. Using a large-box LCDM simulation we carry out a variety of initial analyses with the technique. These include studying the correlation between multi-streaming and density, the identification of structures such as Zel'dovich pancakes and voids, and statistical measurements of quantities such as the volume fraction as a function of the number of streams -- where we find a remarkable scaling relation. Cosmological implications are briefly discussed.
Geometry and Morphology of the Cosmic Web: Analyzing Spatial Patterns in the Universe
我们回顾了宇宙网络的分析手段的基础上使用的Delaunay和Voronoi镶嵌的广泛的工具集。宇宙网络是一种突出而普遍的泡沫状模式，物质在其中以几兆秒差距到一百多兆秒差距的尺度组织起来。首先，我们描述了Delaunay Tessellation Field Estimation（DTFE）。DTFE形式主义恢复宇宙物质分布的层次性和各向异性形态。多尺度形态滤波器（MMF）使用DTFE密度场来提取不同的形态元素-细丝，薄片和簇-基于ScaleSpace分析，该分析在一系列尺度上搜索这些形态。随后，我们讨论了分水岭空洞探测器（WVF），它调用离散分水岭变换来识别宇宙物质分布中的空洞。退伍军人联合会能够确定空洞的位置、大小和形状。分水岭变换也是SpineWeb分析宇宙物质分布的关键要素。它允许通过识别奇点和相应的分界线来确定宇宙物质密度场中的脊和连接壁。最后，我们描述的概念Alphashapes评估的宇宙物质分布的拓扑结构。
Tracing the high-z cosmic web with Quaia: catalogues of voids and clusters in the quasar distribution
Institute of Astronomy and NAO, Bulgarian Academy of Sciences（保加利亚科学院天体物理研究所）；MTA–CSFK Lendület “Momentum” Large-Scale Structure (LSS) Research Group（MTA-CSFK Lendület “Momentum”大尺度结构研究组）；Konkoly Observatory, HUN-REN Research Centre for Astronomy and Earth Sciences（孔科利天文台，匈牙利研究与创新地球与天文学研究中心）；Institute of Physics and Astronomy, ELTE Eötvös Loránd University（罗兰大学物理与天文学研究所）；Instituto de Astrofísica de Canarias（加那利群岛天体物理学研究所）；Departamento de Astrofísica, Universidad de La Laguna（拉帕鲁纳大学天体物理学系）；Département d’Astronomie, Université de G（G大学天文学系）
Zippers and Twisters: Planes of Satellite Galaxies Emerge from Whirling and Shocking Gas Streams in the Cosmic Web
Johns Hopkins University（约翰斯·霍普金斯大学）；NYC College of Technology, City University of New York（纽约市立大学学院技术学院）；Graduate Center, City University of New York（纽约市立大学研究生中心）；Institut d’Astrophsyique de Paris, UMR 7095, CNRS, UPMC Univ.（巴黎天体物理研究所）；Kyung Hee University（庆熙大学）；LSST-DA Catalyst Fellowship, LSST Discovery Alliance（LSST-DA催化剂奖学金，LSST发现联盟）；Centre for Astrophysics Research, University of Hertfordshire（赫特福德大学天体物理学研究中心）
