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Superclusters as future “island universes” – the case of Shapley

Superclusters as future “island universes” – the case of Shapley. Andreas Reisenegger PUC / ESO. Theory/simulations: Rolando Dünner (PUC) Andrés Meza (UChile/UNAB) Pablo A. Araya (Groningen). Observations: Hernán Quintana (PUC) Dominique Proust (Meudon) E. Rodrigo Carrasco (Gemini)

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Superclusters as future “island universes” – the case of Shapley

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  1. Superclusters as future “island universes” – the case of Shapley Andreas Reisenegger PUC / ESO Theory/simulations: Rolando Dünner (PUC) Andrés Meza (UChile/UNAB) Pablo A. Araya (Groningen) Observations: Hernán Quintana (PUC) Dominique Proust (Meudon) E. Rodrigo Carrasco (Gemini) + several others

  2. Outline • Superclusters, Shapley • Superclusters? • Future of structure in CDM cosmology • Spherical collapse, gravitational binding • Redshift-space appearance • Supercluster boundaries & masses • Future plans

  3. F 2MASS Galactic chart

  4. Shapley Supercluster: Redshift catalog of Proust et al. 2006

  5. Shapley Supercluster: Redshift catalog of Proust et al. 2006

  6. Superclusters? • What is a supercluster? • What are its boundaries? So far, definitions have been • Vague: agglomeration of galaxies or clusters, or • Arbitrary: some overdensity, or • Very technical: largest non-percolating structures. • NOT physical

  7. CDM Cosmology • Initially matter-dominated: • hierarchical growth of structure • up to clusters of galaxies (so far) • Now,  is taking over: • expansion accelerates! (supernovae) • bound structures separate from each other • structure formation stops Some structures are dense enough to locally dominate over , but not yet virialized • will collapse within the next Hubble time or so • largest bound structures in the Universe • physical definition of superclusters

  8. Pablo A. Araya, PhD Thesis (Groningen), in preparation

  9. Present (a=1) Distant future (a=100) Pablo A. Araya, PhD Thesis (Groningen), in preparation

  10. Spherical model • Equation of motion for a mass shell: • Analytical solution for the “critical” (marginally bound) shell: (Dünner et al. 2006, MNRAS, 366, 803)

  11. Spherical overdensity criterion vs. simulations 28% 72% 0.26% Dünner et al. 2006

  12. Radial velocity profile Dünner et al. 2006

  13. Real space vs. redshift space Dünner et al., submitted (astro-ph/0611435)

  14. Bound structures in redshift space • Radial velocity from: • true density profile (solid) • NFW density profile (dashed) • simulation (dots: bound=green, unbound=blue) Velocity envelopes derived through spherical collapse from density profiles of simulated structures Dünner et al., submitted (astro-ph/0611435)

  15. Redshift-space boundary • Shape is velocity envelope from: • True density profile (black, solid) • NFW profile + spherical collapse (dashed, red & green) • Calibrate redshift-space density through simulations to be able to fit to observed data Dünner et al., submitted (astro-ph/0611435)

  16. The boundaries of Shapley Dünner et al., in preparation

  17. Pablo A. Araya, PhD Thesis (Groningen), in preparation Supercluster masses Dünner et al., in preparation

  18. Near future • Verify spherical collapse model through Dn- distances to individual clusters in Shapley (Magellan proposal: Quintana, Reisenegger, Melnick, Selman, ...). • Claimed disagreement of predicted vs. observed supercluster mass function (Einasto et al. 2006): verify through redshift-space analysis of simulations vs. SDSS or 2dFGRS. • Improve & compare mass determination methods in simulations & in Shapley. • Center for the Exploration of Superclusters of Galaxies (CESGA): “Milenio” proposal, in 2nd round of evaluation.

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