The Dark Energy Survey

Transcription

1 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 Blanco 4m on Cerro Tololo 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: Survey Operations: 30% of telescope time over 5 years Joe Mohr for the DES Collaboration OIR LRPC Nov '04 Image credit: Roger Smith/NOAO/AURA/NSF 1

2 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, Data Management Abbott, Miller, Smith, Suntzeff and Walker Joe Mohr for the DES Collaboration OIR LRPC Nov '04 2

3 Cluster Redshift Distribution is Sensitive to the Dark Energy Equation of State Parameter w constraints: Raising w at fixed Ω E : dv dzdω = d A 1+ z H z decreases volume surveyed decreases growth rate of density perturbations dn(z) dzdω = dv dz dω n z ( ) c H ( z) d 2 A ( 1+ z) 2 z dz' d A 0 E (z') ( ) is proper distance ( ) = H o E(z) is the Hubble parameter SPT + DES δ + 2 a δ = 4πGρ o δ a where δ δρ ρ o Volume effect Growth effect Joe Mohr for the DES Collaboration OIR LRPC Nov '04 3

4 Precision Cosmology with Clusters Requirements 1. Quantitative understanding of the formation of dark matter halos in an expanding universe 2. Clean way of selecting a large number of massive dark matter halos (galaxy clusters) over a range of redshifts (DES+SPT: 3x10 4 ) 3. Redshift estimates for each cluster (DES photo-z s s ideal) 4. Observables that can be used as mass estimates at all redshifts (SZE flux, weak lensing shear, optical flux) Sensitivity to Mass Technique called self-calibration provides a framework for determining cosmology and the mass-observable relation simultaneously dn(z) dzdω = Joe Mohr for the DES Collaboration OIR LRPC Nov '04 4 c H z 2 1+ z ( ) d A( ) 2 dm M lim dn( M,z) dm

5 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 1000 Element Bolometer Array - 3 to 4 interchangeable bands (90) 150, 250 & 270 GHz - APEX-SZ style horn fed spider web absorbers SZE and CMB Anisotropy 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) NSF-OPP funded & scheduled for Nov 2006 deployment Joe Mohr for the DES Collaboration DoE (LBNL) funding OIR of readout LRPC Nov '04 development 5

6 Survey Area and Depth: Synergy with South Pole Telescope South Pole Telescope 4000 deg2 survey in multiple frequencies (90GHz, 150GHz, 220GHz and 270GHz) Detect and provide mass estimator for ~30,000 clusters through Sunyaev-Zel dovich Effect Dark Energy Survey Measure photometric redshifts for these clusters to z~1.3 Joe Mohr for the DES Collaboration OIR LRPC Nov '04 6

7 Forecasts for SPT+DES Cluster Survey Study of the Dark Energy Cluster constraints on dark energy: The cluster redshift distribution, the cluster power spectrum and 30% accurate mass measurements for 100 clusters between z of Fiducial cosmology (WMAP: σ 8 =0.84, Ω m =0.27); clusters in the 4000 deg 2 SPT survey. Figure from S. Majumdar & J. Mohr The joint constraints on w and Ω m : Curvature free to vary (dashed); fixed (solid) Marginalized constant w 68% uncertainty is (flat) or (curvature varying) Parameter degeneracies complementary to other techniques SPT: Majumdar & Mohr 2003 WMAP: Spergel et al 2003 Joe Mohr for the DES Collaboration OIR LRPC Nov '04 7

8 Galaxy Angular Power Spectrum Cosmology Angular Power Spectrum for 0.90 < z < 1 Figures from Wayne Hu With Planck priors, constraints on a constant equation of state parameter w are better than δw~0.1 Will have a sample of 300 million galaxies with photo-z s s out to z>1 We use the galaxy angular power spectrum within redshift shells, concentrating only on the portion with 50 < l < 300 We marginalize over 5 halo model parameters in each redshift bin Joe Mohr for the DES Collaboration OIR LRPC Nov '04 8

9 DES Weak Lensing Measure shapes for 300 million source galaxies with <z>=0.7 Figures from Wayne Hu Shear-shear and galaxy-shear correlations probe distances and growth rate of structure Systematics shear floor for Blanco is measured to be between (DLS- Tyson) and (cluster lensing- Frieman) LSST WL sample much, much larger and more powerful 4x solid angle 3x source count (better PSF) Systematics requirement much more stringent Joe Mohr for the DES Collaboration OIR LRPC Nov '04 9

10 DES Type Ia Supernovae Repeat observations of 40 deg 2, 10% of survey time Figure from C. Smith, N. Suntzeff ~1900 well-measured riz SN Ia lightcurves,, 0.25 < z < 0.75 Larger sample, improved z-band response compared to ESSENCE, CFHTLS Combination of spectroscopic (25%) and photometric redshifts Develop color typing and SN photoz s s (critical for LSST) DES constraints (assuming σ = 0.2 mag) Joe Mohr for the DES Collaboration OIR LRPC Nov '04 10

11 DES Instrument Reference Design Brenna Flaugher (Fermilab) is the Project Manager for DECam 3556 mm 3 sq-degree camera with 2.2 deg FOV Camera Scroll Shutter Filters Lenses 1575 mm Max of 4 filters: delivered w/ griz( nm) Pixel size 15µm=0.27 Readout time ~10s The Reference Design represents our current design choices and may change with more analysis Joe Mohr for the DES Collaboration OIR LRPC Nov '04 11

12 Camera Reference Design Focal Plane Total cost for the Instrument is $18.4M (excluding institutional overheads). 62 2k x 4k CCDs for main image, 4-side buttable, 15 micron pixels (0.27 arcsec) 8 1k x 1k CCDs for guiding and focus 24 wafer (96 device) R&D run just begun with LBNL Fermilab U Illinois HEP U Chicago (Cash) U Illinois (Cash) Total to date Remainder $13.3M $2.1M $0.5M $0.4M $15.3M $3.1M Joe Mohr for the DES Collaboration OIR LRPC Nov '04 12

13 Data Management Overview Joe Mohr (U Illinois) is the lead for DM Project Data Management System Reliably transfer ~300GB/night produced on 500 nights over 5 years from CTIO to NCSA Process data at NCSA, provide to DES team and community Maintain DES archive over the long term DM Strategy Leverage existing solutions (SM/SN, NSA) Coordinate with LSST DM (@NCSA) and NOAO DPP Early Community Access to Data/Pipelines Raw and reduced data (1 yr after acquisition) Co-add and catalogs (at midpt and again at end of survey) Deliverables 1. The Dark Energy Survey archive for collaboration and community science 2. All processing/reduction pipelines 3. Work w/noao DPP to ensure that DECam guest observers can easily process their data Joe Mohr for the DES Collaboration OIR LRPC Nov '04 13

14 Overview New wide field camera on Blanco in 2009: BIRP recommended to NOAO director Mould that the project go forward DETF will examine all JDEM and LST precursor projects Bulk of funding for camera secured, negotiations continue Forefront studies of cosmic acceleration using four independent techniques constraints on constant w, ~0.4 on dw/dz dz Different systematics- - important crosscheck Different parameter degeneracies- - complementary New resources for community 3 deg 2 camera (70% of time available to community) 500TB image and catalog archive (10x deeper than SDSS, similar solid angle) Project leverages existing funding/investments in time of tight budgets NSF investments in CTIO, NOAO DPP, NCSA and SPT DOE funding flowing to Fermilab and U Illinois HEP Involves DM and DA teams for LSST, drives development of SNAP devices Joe Mohr for the DES Collaboration OIR LRPC Nov '04 14