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Patterns Across the Universe: Clusters and the Cosmic Web. Patterns Across the Universe:. Rien van de Weijgaert Kapteyn Institute, Groningen Summerschool Guillermo Haro 2005 “A Pan-Chromatic View of Clusters of Galaxies & the Large-Scale Structure’’ June 27-July 8, 2005, Puebla, Mexico.
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Patterns Across the Universe: Rien van de Weijgaert Kapteyn Institute, Groningen Summerschool Guillermo Haro 2005 “A Pan-Chromatic View of Clusters of Galaxies & the Large-Scale Structure’’ June 27-July 8, 2005, Puebla, Mexico
Lecture Theme Cosmic Matter and Galaxy Distribution displays salient geometric patterns, the “Cosmic Web”. Clusters are found at the densest spots, the interstices, of this network. These lectures seek to address the issue of the origin, formation and dynamics of the Cosmic Web. It will investigate the position and setting of clusters within the cosmic web, and the role of the web for the formation and evolution of clusters.
Lecture Outline • The Cosmic Foam: Census (observational) • Formation of the Cosmic Web: Linear Theory Gravitational Instability Gaussian random fields Peaks in Gaussian random fields Constrained Random Fields • Formation of the Cosmic Web: Nonlinear Structure Growth: Anisotropic Collapse Hierarchical Clustering Voids • Analysis of the Cosmic Web Modelling superclustering Measures Weblike Patterns/Topologies
Historical Precedents
With warm thanks to my organizer-friends, Manolis & Omar
Cosmology & Geometry:Plato’s Cosmic Scheme Demiurge, divine craftsman, is a mathematician Universe constructed according to Geometric Principles: The Platonic Solids
Cosmology & Geometry:Plato’s Cosmic Scheme ● Four basic constituents of nature: - fire Pyramid - air Octahedron - earth Cube - water Icosahedron ● The Cosmos itself: Dodecahedron
Cosmological Background
the Hot Big Bang One of the greatest and most astonishing triumphs of science, the unravelling of nature, origin and evolution of the Universe Einstein and de Sitter discussing the Universe, in Leiden …
Einstein’s Field Equations … Spacetime becomes a dynamic continuum, integral part of the structure of the cosmos … curved spacetime becomes force of gravity … its geometry rules the world, the world rules its geometry…
Geometry of the Universe:Robertson-Walker Metric The geometry of the 3 homogenous and isotropic space-times can be expressed in terms of its metric, specifying the “distance” between any 2 points in space-time (t,r,θ,φ). These may be shown to have the above expression:Robertson-Walker metric
Friedmann-Robertson-Walker-Lemaitre Universe … for an expanding Universe with ● matter density ρ(t) ● pressure p(t) ● cosmological constant Λ [or elusive dark energy ρv (t)] … whose dynamics is ultimately set by the geometrical term k:
Geometry & Dynamics:Friedmann-Robertson-Walker-Lemaitre Universe Evolution & Fate of the universe determined by one major factor: the ratio of the cosmic (energy) density to , the critical density needed to have a flat Universe: .
Dynamics:Friedmann-Robertson-Walker-Lemaitre Universe Cosmological (energy) densities are typically in the order of that of the critical energy density of the universe. Its value at the current cosmic epoch is:
EADN summerschool, Leiden, July 1995 … Friedmann-Robertson-Walker-Lemaitre Universe of course, since some years … ΛCDM Universe deemed “concordant”…
…The Stars … … a journey…
…Groups & Clusters…
... A Cosmic Filigree …
… Up to the depths of the visible Universe… Our Galaxy …