DES Collaboration Meeting – Dec. 11, Dark Energy Survey Science Proposal Josh Frieman

DES Collaboration Meeting – Dec. 11, Context: Dark Energy Task Force (DETF) Report  Recognized 4 promising Dark Energy probes familiar to DES  Defined Figure of Merit (FoM) for Dark Energy experiments  Envisioned staged approach to DE based on FoM & scale: Stage III: near-term, intermediate-scale projects; FoM~3-5 Stage IV: longer-term, large-scale: LST, JDEM, SKA; FoM~5-10  Recommended immediate start to a Stage III project  Considered 8 `generic’ Stage III projects, 6 of them essentially identical to DES  Proposal should make the case that DES satisfies requirements for a DETF Stage III project, and that multiplicity of methods & control of systematics should yield results toward optimistic end of the Stage III FoM.

DES Collaboration Meeting - Dec. 11, Science Proposal Team Clusters: Mike Gladders, Tim McKay Weak Lensing: Bhuv Jain, Sarah Bridle Supernovae: Bob Nichol, Masao Sako, w/input from Gajus Miknaitis, Ramon Miquel, Rick Kessler BAO: Will Percival, Enrique Gaztanaga, Wayne Hu Other DE Probes: Scott Dodelson Simulations: Gus Evrard, Paul Ricker, Andrey Kravtsov Photo-z’s: Huan Lin, Ofer Lahav Fisher Matrix Mavens: Wayne Hu, Gary Bernstein, Jochen Weller, Scott Dodelson, Zhaoming Ma Reviewers: Joe Mohr, Ramon Miquel, Chris Smith, Gary & Rebecca Bernstein, David Weinberg building on NOAO Proposal (2004) and DETF White Papers (2005)

DES Collaboration Meeting - Dec. 11, Schedule Oct. 18: letter from DOE & NSF Late Oct: Science proposal team formed Phone meetings: 11/3, 11/10, 11/17, 11/28, 12/7 First drafts compiled ~11/27 Revised drafts sent to reviewers 12/2 Reviews received 12/6 Final sections due 12/11 PM Completed science section delivery 12/13 Proposal submission 12/20

DES Collaboration Meeting – Dec. 11, DES Forecasts: Power of Multiple Techniques Ma, Weller, Huterer, etal Assumptions: Clusters: SPT-selected,  8 =0.75, z max =1.5, WL mass calibration (no clustering self-calibration) BAO: l max =300 WL: l max =1000 (no bispectrum or galaxy-shear) Statistical+photo-z systematic errors only Spatial curvature, galaxy bias marginalized Planck CMB prior w(z) =w 0 +w a (1–a) 68% CL geometric geometric+ growth Clusters if  8 =0.9

DES Collaboration Meeting – Dec. 11, I. Clusters and Dark Energy Requirements 1.Understand formation of dark matter halos 2.Cleanly select massive dark matter halos (galaxy clusters) over a range of redshifts 3.Redshift estimates for each cluster 4.Observable proxy that can be used as cluster mass estimate: g(O|M,z) Primary systematics: Uncertainty in g (bias & scatter) Uncertainty in O selection fn.

DES Collaboration Meeting – Dec. 11, Cluster Cosmology with DES 3 Techniques for Cluster Selection and Mass Estimation: Optical galaxy concentration Weak Lensing Sunyaev-Zel’dovich effect (SZE) Cross-compare these techniques to reduce systematic errors Additional cross-checks: shape of mass function; cluster correlations (self-calibration)

DES Collaboration Meeting – Dec. 11, Statistical Weak Lensing Calibrates Cluster Mass vs. Observable Relation Hansen etal Johnston, Sheldon, etal, in preparation

DES Collaboration Meeting – Dec. 11, SZE vs. Cluster Mass: Progress in Simulations Integrated SZE flux decrement depends only on cluster mass: insensitive to details of gas dynamics/galaxy formation in the cluster core robust scaling relations Nagai SZE flux  Adiabatic ∆ Cooling+Star Formation small (~10%) scatter

DES Collaboration Meeting – Dec. 11, Observer Dark matter halos Background sources Statistical measure of shear pattern, ~1% distortion Radial distances depend on geometry of Universe Foreground mass distribution depends on growth of structure

DES Collaboration Meeting – Dec. 11, Cosmic Shear Angular Power Spectrum in Photo-z Slices Shapes of ~300 million galaxies median redshift  z  = 0.7 Primary Systematics: photo-z’s, PSF anisotropy, shear calibration, intrinsic alignments Weak Lensing Tomography DES WL forecasts conservatively assume 0.9” PSF = median delivered to existing Blanco camera: DES should do better & be more stable Huterer Statistical errors shown

DES Collaboration Meeting - Dec. 11, Reducing WL Shear Systematics DECam+Blanco hardware improvements that will reduce raw PSF anisotropy Include Bispectrum and Galaxy-shear: robustness against systematics Red: expected signal Results from 75 sq. deg. WL Survey with Mosaic II and BTC on the Blanco 4-m Bernstein, etal DES: comparable depth: source galaxies well resolved & bright: low-risk (improved systematic) (signal) Shear systematics should be under control at level needed for DES (old systematic) Cosmic Shear

DES Collaboration Meeting – Dec. 11, III. Supernovae Strawman Strategy: Repeat observations in riz of 40 deg 2 `wide & shallow’: ~2600 well-measured SN Ia lightcurves, 0.05 < z < 0.8 Alternative Strategy: `Deep & narrow’ riz of 9 deg 2, spectroscopic follow-up concentrated on Ia’s in ellipticals (lower extinction, better photo-z’s): ~ Ia’s to z~1 Larger sample, improved z-band response compared to ESSENCE, SNLS Issue: what fraction spectroscopic follow-up for distances & sample purity

DES Collaboration Meeting - Dec. 11, IV. Baryon Acoustic Oscillations & Large-scale Structure CMB Angular Power Spectrum SDSS galaxy correlation function Acoustic series in P(k) becomes a single peak in  (r) Bennett, etal Eisenstein etal

DES Collaboration Meeting – Dec. 11, BAO in DES: Galaxy Angular Power Spectrum Probe substantially larger volume and redshift range than SDSS Systematics: photo-z’s, photometric errors, Non-linearity, Scale-dependent bias Controls: Calibration, bispectrum Wiggles due to BAO

DES Collaboration Meeting – Dec. 11, Photometric Redshifts Measure relative flux in four filters griz: track the 4000 A break Estimate individual galaxy redshifts with accuracy  (z) < 0.1 (~0.02 for clusters) Precision is sufficient for Dark Energy probes, provided error distributions well measured. Note: good detector response in z band filter needed to reach z>1 Elliptical galaxy spectrum

DES Collaboration Meeting – Dec. 11, 2006 Spectroscopic Redshift Training Sets for DES Redshift Survey Number of Redshifts Overlapping DES Sloan Digital Sky Survey 70,000, r < 20 2dF Galaxy Redshift Survey 90,000, b J <19.45 VIMOS VLT Deep Survey~60,000, I AB <24 DEEP2 Redshift Survey~30,000, R AB <24.1 Training Sets to the DES photometric depth in place (advantage of a `relatively’ shallow survey)

DES Collaboration Meeting – Dec. 11, 2006 DES Cluster Photometric Redshifts: Simulations & SDSS Results

DES Collaboration Meeting – Dec. 11, 2006 DES griz filters 10  Limiting Magnitudes g24.6 r24.1 i24.0 z % photometric calibration error added in quadrature Key: Photo-z systematic errors under control using existing spectroscopic training sets to DES photometric depth: low-risk Galaxy Photo-z Simulations +VHS JK Improved Photo-z & Error Estimates and robust methods of outlier rejection DES Cunha, etal DES + VHS on ESO VISTA 4-m enhances science reach +Y

DES Collaboration Meeting – Dec. 11, 2006 Variance and Bias of Photo-z Estimates Cunha etal Variance Bias

DES Collaboration Meeting – Dec. 11, Weak Lensing & Photo-z Systematics Ma  (w 0 )/  (w 0 |pz fixed)  (w a )/  (w a |pz fixed)

DES Collaboration Meeting – Dec. 11, BAO & Photo-z Systematics Ma  (w 0 )/  (w 0 |pz fixed)  (w a )/  (w a |pz fixed)

DES Collaboration Meeting – Dec. 11, Will measure Dark Energy using multiple complementary probes, developing these techniques and exploring their systematic error floors Survey strategy delivers substantial DE science after 2 years Relatively modest, low-risk, near-term project with high discovery potential Scientific and technical precursor to the more ambitious Stage IV Dark Energy projects to follow: LSST and JDEM DES in unique international position to synergize with SPT and VISTA on the DETF Stage III timescale DES and the Dark Energy Program