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The Dark Energy Survey DES:Two multi-band surveys: 5000 deg2 g, r, i, z 40 deg2 repeat (SNe) DIRBE dust map DES Summary • Weak Lensing • Baryon Acoustic Oscillations • Supernovae • Cluster Counts → Build new 3 deg2 camera – Survey 2010-2015 (525 nights) – 300,000,000 photometric redshifts Blanco Telescope • 4m diameter equatorial mount telescope. • Located at altitude of 2200m at Cerro Tololo Inter-American Observatory (CTIO) , Chile (Lat. 30o 10’ S, Long. 70 o 49’ W). The Dark Energy Survey Camera: DECam DECam will replace the prime focus cage 4m Blanco telescope DeCam Optical Lay Out C1 C2 C3 C4 C5 978mm Filter 1870mm Expected performance of DECAM, Blanco, and CTIO site Blanco Primary Mirror - 80% encircled energy 0.25 arcsec Optical Corrector Field of View 2.2 deg. Corrector Wavelength Sensitivity <350-1000 nm Effective Area of CCD Focal Plane 3.0 sq. deg. Image CCD pixel format/ total # pixels 2K X 4K/ 520 Mpix Pixel Size 0.27 arcsec/ 15 μm Readout Speed/Noise requirement 250 kpix/sec/ 10 e Median Site Seeing Sept. – Feb. 0.65 arcsec Median Delivered Seeing with Mosaic II on the Blanco 0.9 arcsec Limiting Magnitude: 10 in 1.5” aperture assuming g=24.6, r=24.1, i=24.3, z=23.9, 0.9” seeing Y=20.5 (VHS J=20.4, H=20.0, K=19.4) DES Summary • Weak Lensing • Baryon Acoustic Oscillations • Supernovae • Cluster Counts → Build new 3 deg2 camera – Survey 2010-2015 (525 nights) – 300,000,000 photometric redshifts DES Weak Lensing Current DES WL Work Science requirements: • Image quality • Photometric redshifts Data management: • Object selection • PSF interpolation • Shear measurement Theoretical predictions: • Higher order statistics, small scales i zenith 0 Photo-z with ANNz z = 0.13 Collister & Lahav z input DES + VISTA (YJHKs) z output z output DES (griz) 5-yr alone z=0.08 Collister & Lahav z input Requirements on photoz scatter from intrinsic alignments Bridle & King 2007 == scatter/(1+z) Current DES WL Work Science requirements: • Image quality • Photometric redshifts Data management: • Object selection • PSF interpolation • Shear measurement Theoretical predictions: • Higher order statistics, small scales DES Summary • Weak Lensing • Baryon Acoustic Oscillations • Supernovae • Cluster Counts → Build new 3 deg2 camera – Survey 2010-2015 (525 nights) – 300,000,000 photometric redshifts Expected galaxy power spectrum Turnover Baryon wiggles Adapted from Wayne Hu’s website Are wiggles visible in photo-z surveys? Blake & Bridle 2005 Photo-z error = 0.05 (1+z) (Realistically large) Photo-z error = 0.01 (1+z) (Unrealistically small) Photo-z with ANNz z = 0.13 Collister & Lahav z input DES + VISTA (YJHKs) z output z output DES (griz) 5-yr alone z=0.08 Collister & Lahav z input Are wiggles visible in photo-z surveys? Photo-z error = 0.03 (1+z) ~0.06 ~ DES griz + VISTA Yes! Blake & Bridle 2005 Photo-z error = 0.05 (1+z) ~0.1 ~ DES griz ~DES+VISTA kmax for linear theory Chris Blake DES ~3.5 DES+VISTA ~5 Blake & Bridle 2005 • See also Dolney, Jain & Takada astro-ph/0409445 errors on w from photozs Priors applied Results obtained ~DES+VISTA Chris Blake DES Summary • Weak Lensing • Baryon Acoustic Oscillations • Supernovae • Cluster Counts → Build new 3 deg2 camera – Survey 2010-2015 (525 nights) – 300,000,000 photometric redshifts Supernovae Ia • Deep imaging in riz of 9 deg2 • 10% of survey time, plus a larger fraction of nonphotometric time • Cadence of 5 visits per lunation • ~1000 well-measured SN Ia lightcurves, z~1 • Improved photometric precision via in-situ photometric response measurements SDSS DES Summary • Weak Lensing • Baryon Acoustic Oscillations • Supernovae • Cluster Counts → Build new 3 deg2 camera – Survey 2010-2015 (525 nights) – 300,000,000 photometric redshifts Clusters and Dark Energy ~170 000 clusters with >10 bright red-sequence galaxies, M>~5x1013 Mo to z~1.5 DES Summary • Weak Lensing • Baryon Acoustic Oscillations • Supernovae • Cluster Counts → Build new 3 deg2 camera – Survey 2010-2015 (525 nights) – 300,000,000 photometric redshifts DES Forecasts: Power of Multiple Techniques Assumptions: Clusters: zmax=1.5, WL mass calibration w(z) =w0+wa(1–a) BAO: lmax=300 WL: lmax=1000 (no bispectrum) Statistical+photo-z systematic errors only Spatial curvature, galaxy bias marginalized, Planck CMB prior, 8=0.75 Factor 4.6 improvement over Stage II DETF Figure of Merit: inverse area of ellipse 68% CL DES Forecast Constraints DETF FoM •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 DES Schedule Goals • Last week (Jan 2008): Passed US CD2, CD3a approval • September 2009: DECam maintenance facility operational • January 2010: New Telescope Controls System operational on the Blanco • April 2010: Commission the DES DM at NCSA and transfer simulated data through the DTS to NCSA. • April 2010: Deliver a partial SISPI system to CTIO and begin the integration of SISPI with the telescope controls system, the DTS, and the DES DM system. • July 2010: Deliver DECam to CTIO. • July 2010: Deliver the Optical Corrector to CTIO. • Complete commissioning and make the first science observations while the South Galactic Cap is visible between September 2010 and March 2011. C1 Slumped DES Schedule Goals • Last week (Jan 2008): Passed US CD2, CD3a approval • September 2009: DECam maintenance facility operational • January 2010: New Telescope Controls System operational on the Blanco • April 2010: Commission the DES DM at NCSA and transfer simulated data through the DTS to NCSA. • April 2010: Deliver a partial SISPI system to CTIO and begin the integration of SISPI with the telescope controls system, the DTS, and the DES DM system. • July 2010: Deliver DECam to CTIO. • July 2010: Deliver the Optical Corrector to CTIO. • Complete commissioning and make the first science observations while the South Galactic Cap is visible between September 2010 and March 2011. DES Summary • Weak Lensing • Baryon Acoustic Oscillations • Supernovae • Cluster Counts → Build new 3 deg2 camera – Survey 2010-2015 (525 nights) – 300,000,000 photometric redshifts END Spectroscopic Redshift Training Sets for DES Redshift Survey Overlap with DES Number of Redshifts Overlapping DES Sloan Digital Sky Survey Southern Equatorial Stripe 70,000, r<20 (Stripe 82) median z=0.1–0.6 depending on the sample 2dF Galaxy Redshift Survey Most of SGP strip and SGP 90,000, bJ<19.45 random fields median z = 0.1 VIMOS VLT Deep Survey 3 fields at RA/Dec = 2217+00, ~60,000, IAB<24 0226–04, 0332–28 median z ~ 0.8 DEEP2 Redshift Survey 2 fields at RA/Dec = 2330+00, ~30,000, RAB<24.1 0230+00 median z ~ 1