Presentations to Blanco Instrument Review Panel

1
Presentations to Blanco Instrument Review Panel

• Intro and Science 1 Mohr
• Science 2 and Context Frieman
• Survey Design Annis
• Instrument Flaugher
• Optical Design Kent
• Data Management Plante
• Project Management Peoples

2
Toward an Understanding of the Dark Energy/
Cosmic Acceleration

1. Measuring (relative) distances or volumes out to
   z2
2. Measuring the growth rate of cosmic structures
3. Detecting dark energy clustering in the power
   spectrum of density fluctuations
4. Measure evolution of gravitational potential
   wells using the Integrated Sachs-Wolfe effect
5. Laboratory experiments and theoretical progress

3
Key Techniques for Measuring the Dark Energy
Equation of State Parameter

1. Type Ia Supernovae as standard candles
2. Power spectrum measurements using galaxies or
   clusters
3. Cosmic Microwave Background anisotropy
4. Weak lensing measurements
5. Galaxy cluster surveys

4
The Dark Energy Survey

• A study of the dark energy using four independent
  and complementary techniques
• Galaxy cluster surveys
• Galaxy angular power spectrum
• Weak lensing
• SN Ia distances
• Two linked, multiband optical surveys
• 5000 deg2 g, r, i and z
• Repeated observations of 40 deg2
• Instrument and schedule
• New 3 deg2 camera on the Blanco 4m on Cerro
  Tololo
• Construction 2004-2009
• Survey Operations 30 of telescope time over 5
  years

5
The Dark Energy Survey Collaboration

• Fermilab- Camera building, Survey Planning and
  Simulations
• Annis, Dodelson, Flaugher, Frieman, Gladders,
  Hui, Kent, Lin, Limon, Peoples, Scarpine,
  Stebbins, Stoughton, Tucker and Wester
• Carnegie Fellow, Carnegie Observatories
• U Illinois- Data Management, Data Acquisition,
  SPT
• Brunner, Karliner, Mohr, Plante, Selen and Thaler
• U Chicago- SPT, Simulations, Corrector
• Carlstrom, Dodelson, Frieman, Hu, Kent, Sheldon
  and Wechsler
• LBNL- Red Sensitive CCD Detectors
• Aldering, Bebek, Levi, Perlmutter and Roe
• CTIO- Telescope Camera Operations
• Abbott, Smith, Suntzeff and Walker

6
Cluster Survey Studies of the Dark Energy are
Complementary and Competitive

• Cluster constraints on dark energy
• The cluster redshift distribution, the cluster
  power spectrum and 30 accurate mass measurements
  for 100 clusters between z of 0.3-1.2
• Fiducial cosmology (WMAP s80.84, Wm0.27)
  29000 clusters in the 4000 deg2 SPT survey.
• The joint constraints on w and Wm
• Curvature free to vary (dashed) fixed (solid)
• Marginalized constant w 68 uncertainty is 0.046
  (flat) or 0.071 (curvature varying)
• Parameter degeneracies complementary

SPT Majumdar Mohr 2003 SNAP Perlmutter
Schmidt 2003 WMAP Spergel et al 2003
7
Cluster Redshift Distribution is Sensitive to the
Dark Energy Equation of State Parameter
w constraints

• Raising w at fixed WE
• decreases volume surveyed

• decreases growth rate of density perturbations

8
Precision Cosmology with Clusters

• Requirements
• Quantitative understanding of the formation of
  dark matter halos in an expanding universe
• Clean way of selecting a large number (104) of
  massive dark matter halos (galaxy clusters) over
  a range of redshifts
• Crude redshift estimates for each cluster
• Observables that can be used as mass estimates at
  all redshifts
• Technique called self-calibration provides a
  framework for determining cosmology and
  mass-observable relation simultaneously

9
10m South Pole Telescope (SPT)and 1000 Element
Bolometer Array

• Low noise, precision telescope
• 20 um rms surface
• 1 arc second pointing
• 1.0 arcminute at 2 mm
• chop entire telescope
• 3 levels of shielding
• 1 m radius on primary
• inner moving shields
• outer fixed shields

SZE and CMB Anisotropy - 4000 sq deg SZE
survey - deep CMB anisotropy fields - deep
CMB Polarization fields
People Carlstrom (UC) Holzapfel (UCB) Lee
(UCB,LBNL) Leitch (UC) Meyer (UC) Mohr (U
Illinois)Padin (UC) Pryke (UC) Ruhl
(CWRU) Spieler (LBNL) Stark (CfA)
1000 Element Bolometer Array - 3 to 4
interchangeable bands (90) 150, 250 270
GHz - APEX-SZ style horn fed spider web
absorbers
NSF-OPP funded scheduled for Nov 2006
deployment DoE (LBNL) funding of readout
development
10
SPT Structure and Shielding
11
SPT Survey Region

• SPT will survey all the extragalactic sky south
  of declination d-300
• This corresponds to approximately 4000 deg2 of
  reasonably clean sky
• north of d-750
• 20hr lt a lt 7hr
• This region is easily observable with the Blanco
  4m on Cerro Tololo

12
DES Cluster Photo-zs

• DES data will enable cluster photometric
  redshifts with dz0.02 for all SPT clusters out
  to z1.3

• Uses Monte-carlo estimates of galaxy photo-z
  uncertainties, which include appropriate
  photometric noise Huan Lin
• Uses halo occupation number N(M) measured in 100
  local groups and clusters Y-T Lin, Mohr
  Stanford 2004
• Adopts redshift evolution of N(M)(1z) and
  passive evolution of galactic stars

Figure from Huan Lin
13
Why a Large SZE Cluster Survey?

• Improved halo mass estimates- the mass-observable
  relations in the optical are not as clean
• 100 rms in optical- see below- versus 10-25
  in SZE
• Improved cluster selection- projection and
  environment issues are not as severe (optical
  data complementary)
• What about X-ray surveys (serendipitous and with
  DUO)?

14
DES Galaxy Angular Power Spectrum

• DES main survey will yield photo-zs on
  approximately 300 million galaxies extending
  beyond a redshift z1
• Photo-z uncertainties are too large to allow a
  full study of the 3D galaxy clustering, but we
  can study the angular clustering within redshift
  shells to z1
• Features in the angular power spectrum reflect
  standard rods that follow from simple physical
  arguments and can be calibrated using CMB
  anisotropy data.
• Apparent sizes of features provide angular
  diameter distances to each redshift shell (i.e.
  Cooray et al 2001). The clustering amplitude is
  unimportant, and so the unknown galaxy bias is no
  problem.

15
Galaxy Angular Power Spectrum Cosmology
Figures from Wayne Hu

• With Planck priors, constraints on a constant
  equation of state parameter w are better than
  dw0.1

• We use the galaxy angular power spectrum within
  redshift shells, concentrating only on the
  portion with 50 lt ell lt 300
• We marginalize over 5 halo model parameters in
  each redshift bin

16
Presentations to Blanco Instrument Review Panel

• Intro and Science 1 Mohr
• Science 2 and Context Frieman
• Survey Design Annis
• Instrument Flaugher
• Optical Design Kent
• Data Management Plante
• Project Management Peoples