The Dark Energy Survey (DES)

The Dark Energy Survey (DES)

Sarah Bridle, UCLOn behalf of the DES Collaboration

The Dark Energy Survey• Study Dark Energy using 4 complementary techniques: I. Cluster Counts II. Weak Lensing III. Baryon Acoustic Oscillations IV. Supernovae

• Two multi-band surveys 5000 deg2 g, r, i, z 40 deg2 repeat (SNe)

• Build new 3 deg2 camera and data management system Survey 2010-2015 (525 nights) Response to NOAO AO

Blanco 4-meter at CTIO

300,000,000 photometric redshifts

The Dark Energy Survey• Study Dark Energy using 4 complementary techniques: I. Cluster Counts II. Weak Lensing III. Baryon Acoustic Oscillations IV. Supernovae

• Two multi-band surveys 5000 deg2 g, r, i, z 40 deg2 repeat (SNe)

• Build new 3 deg2 camera and data management system Survey 2010-2015 (525 nights) Response to NOAO AO

Blanco 4-meter at CTIO

300,000,000 photometric redshifts

The DES CollaborationFermilab: J. Annis, H. T. Diehl, S. Dodelson, J. Estrada, B. Flaugher, J. Frieman, S. Kent, H. Lin, P. Limon, K. W. Merritt, J. Peoples, V. Scarpine, A. Stebbins, C. Stoughton, D. Tucker, W. WesterUniversity of Illinois at Urbana-Champaign: C. Beldica, R. Brunner, I. Karliner, J. Mohr, R. Plante, P. Ricker, M. Selen, J. ThalerUniversity of Chicago: J. Carlstrom, S. Dodelson, J. Frieman, M. Gladders, W. Hu, S. Kent, R. Kessler, E. Sheldon, R. WechslerLawrence Berkeley National Lab: N. Roe, C. Bebek, M. Levi, S. PerlmutterUniversity of Michigan: R. Bernstein, B. Bigelow, M. Campbell, D. Gerdes, A. Evrard, W. Lorenzon, T. McKay, M. Schubnell, G. Tarle, M. TecchioNOAO/CTIO: T. Abbott, C. Miller, C. Smith, N. Suntzeff, A. WalkerCSIC/Institut d'Estudis Espacials de Catalunya (Barcelona): F. Castander, P. Fosalba, E. Gaztañaga, J. Miralda-EscudeInstitut de Fisica d'Altes Energies (Barcelona): E. Fernández, M. MartínezCIEMAT (Madrid): C. Mana, M. Molla, E. Sanchez, J. Garcia-BellidoUniversity College London: O. Lahav, D. Brooks, P. Doel, M. Barlow, S. Bridle, S. Viti, J. Weller University of Cambridge: G. Efstathiou, R. McMahon, W. Sutherland University of Edinburgh: J. Peacock University of Portsmouth: R. Crittenden, R. Nichol, R. Maartnes, W. PercivalUniversity of Sussex: A. Liddle, K. Romer

plus postdocs and students

The Dark Energy Survey UK Consortium

(I) PPARC funding: O. Lahav (PI), P. Doel, M. Barlow, S. Bridle, S. Viti, J. Weller (UCL), R. Nichol (Portsmouth), G. Efstathiou, R. McMahon, W. Sutherland (Cambridge) J. Peacock (Edinburgh)

Submitted a proposal to PPARC requesting £ 1.7M for the DES optical design. In March 2006, PPARC Council announced that it “will seek participation in DES”. PPARC already approved £220K for current R&D.

(II) SRIF3 funding: R. Nichol, R. Crittenden, R. Maartens, W. Percival (ICG Portsmouth) K. Romer, A. Liddle (Sussex)

Funding the optical glass blanks for the UCL DES optical work

These scientists will work together through the UK DES Consortium. Other DES proposals are under consideration by US and Spanish funding agencies.

The Dark Energy Survey Camera: DECam

DECam will replace the prime focus cage

4m Blanco telescope

Expected performance of DECAM, Blanco, and CTIO site

Blanco Effective Aperture/ f number @ prime focus 4 m/ 2.7

Blanco Primary Mirror - 80% encircled energy 0.25 arcsec

Optical Corrector Field of View 2.2 deg.

Corrector Wavelength Sensitivity <350-1000 nm

Filters SDSS g, r, i, z (400-1000 nm)

Effective Area of CCD Focal Plane 3.0 sq. deg.

Image CCD pixel format/ total # pixels 2K X 4K/ 520 Mpix

Guide, Focus & Wavefront Sensor CCD pixel format 2K X 2K

Pixel Size 0.27 arcsec/ 15 μm

Readout Speed/Noise requirement 250 kpix/sec/ 10 e

Survey Area SPT overlap SDSS stripe 82 Connection region

5,000 sq. deg. totalRA -60 to 105, DEC -30 to -65RA -75 to -60 , DEC -45 to -65RA -50 to 50, Dec -1 to 1RA 20 to 50, Dec -30 to -1

Survey Time/Duration 525/5 (nights/years)

Median Site Seeing Sept. – Feb. 0.65 arcsec

Median Delivered Seeing with Mosaic II on the Blanco 0.9-1.0 arcsec (V band)

Limiting Magnitude: 10 in 1.5” aperture assuming 0.9” seeing g=24.6, r=24.1, i=24.3, z=23.9

Limiting Magnitude: 5 for point sources assuming 0.9” seeing g=26.1,r=25.6, i=25.8, z=25.4

DeCamOptical Lay Out

C1

C2 C3

Filter

C4C5

978mm

1870mm

i zenith 0

DES and VISTA synergy

DES (griz) DES+VISTA(JK)

VISTA J (<21) and K (<19) would improve photo-z by a factor of 2 for z> 1F. Abdalla, M. Banerji, OL, H. Lin, et al.

DES Forecasts: Power of Multiple Techniques

Assumptions:Clusters: 8=0.75, zmax=1.5,WL mass calibration

BAO: lmax=300WL: lmax=1000(no bispectrum)

Statistical+photo-z systematic errors only

Spatial curvature, galaxy biasmarginalized,Planck CMB prior

Factor 4.6 improvement over Stage II

w(z) =w0+wa(1–a) 68% CL

DETF Figure of Merit: inversearea of ellipse

DES Forecast Constraints

•DES+Stage II combined = Factor 4.6 improvement over Stage II combined•Consistent with DETF range for Stage III DES-like project•Large uncertainties in systematics remain, but FoM is robust to uncertainties in any one probe, and we haven’t made use of all the information

DETF FoM