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

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

F 2MASS Galactic chart

Shapley Supercluster: Redshift catalog of Proust et al. 2006

Shapley Supercluster: Redshift catalog of Proust et al. 2006

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

 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

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

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

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

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

Radial velocity profile Dünner et al. 2006

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

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

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/ )

The boundaries of Shapley Dünner et al., in preparation

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

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 2 nd round of evaluation.