Superclusters%20as%20future%20

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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
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Outline

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

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F
2MASS Galactic chart
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Shapley Supercluster Redshift catalog of Proust
et al. 2006
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Shapley Supercluster Redshift catalog of Proust
et al. 2006
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(No Transcript)
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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

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?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

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Pablo A. Araya, PhD Thesis (Groningen), in
preparation
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Present (a1)
Distant future (a100)
Pablo A. Araya, PhD Thesis (Groningen), in
preparation
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Spherical model

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

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Spherical overdensity criterion vs. simulations

• 28
• 72
• 0.26

Dünner et al. 2006
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Radial velocity profile
Dünner et al. 2006
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Real space vs. redshift space
Dünner et al., submitted (astro-ph/0611435)
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Bound structures in redshift space

• Radial velocity from
• true density profile (solid)
• NFW density profile (dashed)
• simulation (dots boundgreen, unboundblue)

Velocity envelopes derived through spherical
collapse from density profiles of simulated
structures
Dünner et al., submitted (astro-ph/0611435)
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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)
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The boundaries of Shapley
Dünner et al., in preparation
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Supercluster masses
Pablo A. Araya, PhD Thesis (Groningen), in
preparation
Dünner et al., in preparation
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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.