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Cluster Cosmology at LPPC

Cluster Cosmology at LPPC. Illuminating Dark Energy with BCS and PISCO F. William High 2 nd Year Grad Student Harvard Univ Dept of Physics Monday, 21 August 2006. Cluster Cosmology. Redshift z: 1 + z = λ (observed) / λ (emitted). Today.

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Cluster Cosmology at LPPC

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  1. Cluster Cosmology at LPPC Illuminating Dark Energy with BCS and PISCO F. William High 2nd Year Grad Student Harvard Univ Dept of Physics Monday, 21 August 2006

  2. Cluster Cosmology Redshift z: 1 + z = λ(observed) / λ(emitted) Today Big Bang Galaxies start forming Dark Energy takes effect Dark Energy dominates Galaxies start clustering t ~ 14 Gyr t ~ 9 Gyr t ~ 7 Gyr t ~ 3 Gyr t = 0 z = 0 z ~ ½ z ~ 1 z ~ 2 z = ∞ t ~ 1 Gyr z ~ 6 Clusters@LPPC

  3. Cluster Cosmology: Illuminating Dark Energy • Accelerating expansion • Λ: Einstein’s cosmo-logical constant • w: eqn of state (w = -1) • Cluster abundance versus redshift • Depends heavily on Λ and w • Overall normalization depends onσ8 1/10 of the sky Number of clusters redshift Clusters@LPPC

  4. Discovering Clusters • SZ effect • APEX, ACT, SPT, … • Redshift independent signal in mm mm-wave X-ray Clusters@LPPC

  5. THE REST BCS (500 clusters), then PISCO (3000 clusters), then DES (the rest) Clusters@LPPC

  6. Mass of clusters? Solution: BCS Distance to clusters? Solution: PISCO Two Challenges Probability: Matter evolution: Observable: Clusters@LPPC

  7. BCS • Blanco Cosmology Survey • Pre-SPT • To z ~ 1 • Training set for SPT and PISCO • Weak gravitational lensing to calibrate SZ cluster mass estimator • PI: Joe Mohr (U Illinois) Clusters@LPPC

  8. PISCO • Parallel Imager for Southern Cosmological Observations • Dedicated camera to measure redshift of high-z clusters • Field of view matched to size of high redshift clusters: 5’ = 1 Mpc at z = ½, clusters are 1-10 Mpc across • Highest possible efficiency broadband photometer: 4 simultaneous bands • To be mounted on 6.5m Magellan, Chile Clusters@LPPC

  9. PISCO: Photo-z LRG spectrum • Principle: measure differential broadband flux (color) of objects with broad features in spectrum • Photo-z gives redshifts (to 10%) from the colors of luminous red galaxies (LRG) • Cluster member galaxies have scatter in redshift at 3% level • PISCO measures photo-z’s of all galaxies in a cluster at once, in a single exposure Clusters@LPPC

  10. PISCO: Design Ideal broadband photometer! Dichroic beamsplitters define bandpasses Clusters@LPPC

  11. PISCO: Design Clusters@LPPC

  12. Use weak gravitational lensing to calibrate other cluster mass-observables Improve cluster mass estimation for all future surveys Status: first year data reduced, ready to do start WL study in September Characterize DE with clusters quickly, cheaply, efficiently Can get z’s of all SPT clusters in 10 nights at Magellan! Status: CCD’s in hand, CCD control online, design soon finalized, Carnegie enthusiastic, … CC@LPPC Summary BCS PISCO Clusters@LPPC

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