1 / 95

Dynamics & Multiscale Morphology Cosmic Web

Dynamics & Multiscale Morphology Cosmic Web. Rien van de Weygaert 3 rd KIAS Workshop, Oct 27-28, Seoul, 2008. Collaboration & References: Pablo Araya- Melo Miguel Aragon- Calvo

machiko-rin
Download Presentation

Dynamics & Multiscale Morphology Cosmic Web

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Dynamics & Multiscale Morphology Cosmic Web Rien van de Weygaert 3rd KIAS Workshop, Oct 27-28, Seoul, 2008

  2. Collaboration & References: Pablo Araya-Melo Miguel Aragon-Calvo Erwin Platen Emilio Romano-Diaz Willem Schaap Bernard Jones GertVegter (comp. geometry & topology)

  3. Foams in Nature

  4. Foams in Nature • The largest complex pattern found in nature is Megaparsec Scale: • the Cosmic Web • manifestation of the gravitational origin, emergence and growth of ALL structure in the cosmos …

  5. The Cosmic Web Stochastic Spatial Pattern of  Clusters,  Filaments &  Walls around  Voids in which matter, (DM, gas, gal’s) has agglomerated

  6. The Cosmic Web Significance:  Manifestation mildly nonlinear clustering: Transition stage between linear phase and fully collapsed/virialized objects  Weblike configurations contain cosmological information: e.g. Void shapes & alignments (recent study J. Lee 2007)  Cosmic environment within which to understand the formation of galaxies.

  7. Web Analysis • Translate discrete galaxy/particle distribution into continuous density field/image: - DTFE: Delaunay Tessellation Field Estimator • (Post)processing: - filtering/smoothing image - identifying clusters (peaks in image) - identifying filaments/walls: * MMF & spine (Morse theory) - tracing void regions: * watershed transform (Morse theory) - topological aspects * alpha shapes

  8. The Cosmic Web • Web Discretely Sampled: • By far, most information on the • Cosmic Web concerns • discrete samples: • observational: • Galaxy Distribution • theoretical: • N-body simulation particles

  9. Power of Tessellations

  10. Multiscale MorphologyFilter filament MMF dissection of cosmic web into sheets, filaments, clusters … cluster sheet

  11. Spine of the Cosmic Web: Morse complex & search for singularities

  12. Watershed Void Identification

  13. Alpha Shapes Alpha Shape of cosmological simulation left to right: alpha value increases. LSS Topology

  14. Cosmic WebEvolution &Dynamics

  15. Dynamical Evolution Cosmic Web

  16. Dynamical Evolution Cosmic Web ● hierarchical structure formation ● anisotropic collapse ● void formation: asymmetry overdense vs. underdense

  17. Anisotropic Collapse ●Gravitational Instability: - any small initial deviation from sphericity of a collapsing cloud gets magnified - gravitational collapse proceeds along sequence: ● collapse along smallest axis planar geometry wall ● collapse medium axis elongated filament ● full 3-D collapse clump halo  clump/halo virialization cosmic object (courtesy: A. Kravtsov).

  18. Formative agent of the Cosmic Web: Tidal strain induced my the Megaparsec Matter Distribution: - anisotropic collapse of structures - connection clusters-filaments: clusters main agent for stretching filaments

  19. Ellipsoidal Collapse short axis medium axis spherical long axis Self-gravity  Internal tidal shear (due to shape)  External tidal shear

  20. Cosmic Web & Clusters Perseus Cluster (A426)

  21. Tidal Constraints: Example: elongated filamentary feature Constrained Field:

  22. Cosmic Web Theory: Specification Cluster Node Locations & Orientation: Outline Cosmic Web •  Spatial structure of Cosmic Web structure present in primordial density field. •  Geometry of primordial field mainly filamentary (not Zel’dovich sheets), by sheer of statistics Gaussian field. • Filaments defined by tidal field imposed by cluster patches. • Incremental improvement of cosmic web spatial outline by inserting more and more clusters Bond & Myers 1996 Bond et al. 1996

  23. Cosmic Web Theory : Specification Cluster Node Locations & Orientation: Outline Cosmic Web Bond & Myers 1996 Bond et al. 1996

  24. Cosmic Web Theory : Specification Cluster Node Locations & Orientation: Outline Cosmic Web •  Spatial structure of Cosmic Web structure present in primordial density field. •  Geometry of primordial field mainly filamentary (not Zel’dovich sheets), by sheer of statistics Gaussian field. • Filaments defined by tidal field imposed by cluster patches. • Incremental improvement of cosmic web spatial outline by inserting more and more clusters Bond et al. 1996

  25. Multiscale Nature Anisotropic Collapse • Structure arises over • a vast range of scales • Small scales: • fully collapsed objects • - Very large scales: • still linear (& Gaussian) • Medium Mpc scales: • weblike features • Two analytical formalisms: • statistical Press-Sch. •  dynamical PeakPatch

  26. Hierarchical Pattern Formation

  27. Hierarchical Void Evolution: • “Local” Excursion Set Approach •  Two-barrier description: • - void merger • - void collapse •  Peaked Void Size Distribution Void Merging Void Collapse

  28. Galaxy/Halo&Web Environment

  29. Halo Shape Alignments Halo & Galaxy Environmental Influences Halo Shape Alignment evolution Filaments: Haloes elongated along filament Walls: Haloes elongated within plane wall (major axis in wall) Orientation weakens in time Effect stronger for low-mass haloes

  30. Spinning the Galaxies

  31. Spinning the Galaxies Spinning Up a collapsing protogalaxy by Tidal Torque

  32. Spinning the Galaxies Connection Galaxy Spin Cosmic Web Spinning the Galaxies: Tidal Forces that also Shape Cosmic Web

  33. Cosmic Web: Environmental Impact Halo & Galaxy Formation: Environmental influences • Environmental dependence strongest wrt. Alignments: - halo shape - halo spin direction  To be understood from the crucial role of tidal forces in shaping the Cosmic Web

  34. Cosmic Web: Environmental Impact Halo & Galaxy Formation: Environmental influences  Environmental dependence on the halo spin distribution To a large extent influenced by presence of unbound particles Halo Spin distribution in clusters, filaments & sheets

  35. Halo Spin Alignments

  36. Halo Spin Alignments Halo & Galaxy Environmental Influences Halo Spin Alignment evolution Filaments: High-mass haloes: always perpendicular Low-mass haloes: starting perpendicular, they evolve to parallel Walls: High & Low-mass: always in plane of wall

  37. Filament-Galaxy alignment SDSS DR5

  38. Filament-Galaxy alignment SDSS DR5 Jones et al. 2008 (in prep.) edge-on galaxies

  39. Cosmic WebAnalysis

  40. Exploiting the Adaptive Nature of Voronoi/Delaunay Tessellations Natural Neighbour Interpolation Discrete Point/Galaxy Distribution Continuous Field (Sibson 1980, 1981; Watson 1992)

  41. Point Sample Continuous Field Aspects: ● Anisotropy of Structural Features ● Hierarchical Infrastructure ● Voids, cq. empty regions ● Inhomogeneous Sampling

  42. Dual Tessellations Voronoi Delaunay Voronoi Vertices: Centers Circumscribing Spheres 4 nuclei Delaunay Tetrahedron

  43. Delaunay Tessellation Delaunay Tetrahedron: Set of 4 nuclei, circumscribing sphere not containing any other nuclei Space-Covering Complete Set Delaunay Tetrahedra: Delaunay Tessellation Voronoi Tessellation & Delaunay Tessellation: Duals Delaunay Tetrahedra: Natural Multidimensional Interpolation Volume

  44. NN-neighbour Interpolation Kernel

More Related