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An Optical Counterpart to the SPT

A Wide Area Imaging Survey? Constraints Possibilities. An Optical Counterpart to the SPT. Jim Annis Fermilab Josh Frieman Fermilab/U Chicago Joe Mohr U Illinois. A1576 z=0.30 Stefano Zibetti/SDSS. The SPT. 4000 sq-degrees SZ survey

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An Optical Counterpart to the SPT

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  1. A Wide Area Imaging Survey? Constraints Possibilities An Optical Counterpart to the SPT Jim Annis Fermilab Josh Frieman Fermilab/U Chicago Joe Mohr U Illinois A1576 z=0.30 Stefano Zibetti/SDSS

  2. The SPT • 4000 sq-degrees SZ survey • > 20,000 clusters w/o redshifts • ~80% at z < 1 • How does one followup?

  3. Z=0.138 Z=0.041 Z=0.277 Z=0.377 Example color cluster images from the SDSS

  4. Finding clusters in SDSS data Z=0.165 • Early type galaxies label groups and clusters • Very uniform old stellar populations & colors • Widefield multicolor CCD data has revitalized optical cluster finding • Cluster members are the reddest galaxies at each redshift • Clusters in position-color space • Need location, richness, size SDSS image of Abell 1553

  5. g-r color i magnitude Finding red sequence clusters E/SO ridgeline • Clustering in position-color space essentially eliminates contamination by projection • Gladders & Yee (2000), Goto et al. (2001), Annis et al. (2003) • E/SO ridgeline provides extremely accurate (z0.01) photometric redshift • Red sequence in place throughout SDSS volume and beyond, to z>1…. Red sequence galaxies at z=1.27 (van Dokkum et al, 2000)

  6. Elliptical Galaxy Spectrum g r i

  7. Excellent photometric redshifts! The maxBCG sample: redshift

  8. Observed richness distribution: >3x105 over 2100  M>5x1013M☼ The maxBCG sample: detection and richness • Likelihood based on BCG fit and presence of E/SO ridgeline • Cluster center defined by ‘BCG’ galaxy • Richness estimated by Ngals>0.4L* (also Ltot, etc…) • Redshift estimated by photoz techniques • Outputs include cluster info and member list

  9. Ng=1 v=144 Ng=2 v=253 Ng=6 v=352 Ng=9 v=374 Measure v within a projected R200 for each richness Ng=36 v=815 Ng=25 v=670

  10. An Optical Survey CounterpartTo SPT • One follows up by a 4000 square degree imaging survey, in 4 bandpasses, to i~24. This allows: • Photometric redshifts for ~25,000 SZ clusters • Optically selected sample of clusters • redshift and mass estimates • Weak lensing mass estimates of these clusters • Weak lensing cosmic shear measurements • with photo-z tomography • Galaxy clustering on large scales to z ~ 1 • Galaxy-galaxy lensing • … and much more.

  11. Sketch of a Project Back of the envelopes should convince you this is a doable. Simple things first, before complicated … these are the times before early days

  12. Existing Instruments • SDSS: not deep enough • z = 0.3 – 0.5 • CFHT Legacy Survey • 20 N declination (2 airmass @ -40 dec, meridian) • PanStarrs • 20 N declination (2 airmass @ -40 dec, meridian) • Mosaic Camera on Blanco 4m • FOV too small. • Otherwise ok… (1.5 airmasses at –75 dec, meridian) • LSST • 2013 (?)

  13. CTIO Blanco 4m • Collecting area:10 m^2 • Prime focus: • f/2.87 • 15 micron pixels => 0.267”/pixel • Field of view (diameter): • Current: 0.8 degree • Need: 1.8 degree • NOAO Long Range Plan • SOAR high resolution imaging • Gemini South: deep imaging • Blanco 4m wide field imaging

  14. How Much Time • Assume ¼ time of big telescope, 50% useful • 3 years to finish survey • 10 hours * 3 good nights * 10 months * 3 years • = 1000 hours • 4000 sq-degree and 1000 hours = 15 min/sq-degree • Conservative- perhaps a factor of 2 more, from 75% useful time and 5 years to completion

  15. Depth • 0.5 L* at z = 1 in i = 24 AB • z = 23, sky brighter • Factor of 40 times SDSS depths • i = 20.25 (10-sigma) at z=0.35, • >90% completeness and efficiency • i = 24 (10-sigma) at z = 1 • Collecting area: 4m > 2.5m x2 • Seeing: 0.8” < 1.2” x2 • Integration 540sec > 55sec x10 = x40 • 4m per filter/sq-degree • Imager is 2.25 sq-degrees

  16. Imager • Assume 0.25”/pixel • Assume 1.5 degee per side focal plane • => 2.25 sq-degree • => 20k x 20k pixels • Big, but state of the art last January: Megacam is 16k x 16k • Recall, we dream two years out, 4 years to light Megacam, at CFHT

  17. Large format cameras Megacam, at CFHT 36 4k x 2k 300 Megapix 2003 CFH12k 12 4k x 2k 100 Megapix 2000 SDSS 30 2k x 2k 120 Megapix 1998 Megacam at MMT 36 4k x 2k 300 Megapix 2003

  18. CDF’s Silicon Vertex Detector

  19. Wide field corrector Camera CCDs/detectors Electronics Readout Control Mechanical Vacuum systems Cooling systems Data acquisition system Survey obs strategy Standard star strategy Science Software Calibration pipeline Coadd pipeline Galaxy measurement pipeline Cluster finding pipeline Data production Data distribution Science analysis Elements of a Survey Science case! for proposals

  20. What to do next: Form a collaboration Begin working with CTIO Work towards proposals to NSF and DOE Spend 2 years raising money and designing survey … maybe in 2005 start building? … in 2010, work the SPT and optical catalogs. End Thoughts • 4000 sq-degrees to i=24 in 4 filters is possible (!) • All clusters at z < 1 given redshifts to < 0.02 • Full utilization of SPT observations • Cosmology from the optical/weak lensing cluster surveys

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