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SNAP-L

SNAP-L. A wide field imager for dark energy … and more !. Jean-Paul KNEIB LAM, Marseille, France. The SNAP-L Mission. SNAP-L is a ~2m telescope with a wide field optical/near-IR camera and a 3D optical/near-IR spectrograph.

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SNAP-L

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  1. SNAP-L A wide field imager for dark energy … and more ! Jean-Paul KNEIB LAM, Marseille, France Jean-Paul KNEIB - prospective spatial PNG

  2. The SNAP-L Mission SNAP-L is a ~2m telescope with a wide field optical/near-IR camera and a 3D optical/near-IR spectrograph. SNAP-L is a project led by the Department of Energy (US particle physicist community) started in ~1999 with international partners: • France: through the spectrograph development and scientific expertise (SN, WL) [INSU+IN2P3] • Sweden: SN science • Canada: WL science • Other countries interested … and possibilities to have a stronger contribution in the project. Jean-Paul KNEIB - prospective spatial PNG

  3. SNAP-L: the concept A 2 meter class telescope, 3 mirror anastigmatic design Provide a wide field flat focal plane, FOV >0.7 square degrees Covering ~350 to ~1700 nm On a L2 orbit for stability and low background Jean-Paul KNEIB - prospective spatial PNG

  4. SNAP-L: focal plane spectrographe 3D IFU slicer visible+IR R=100-200 3’’x3’’ , [0.35-1.7]mm 9 filters 6 visibles 3 IR Imager visible + IR pixel scale = 0.10 arcsec/pixel (visible), 0.17 arcsec/pixel (NIR) 36 4kX4k CCDs [0.35-1]mm 0.5 Gigapixels, 36 2kX2k HgCdTe [1-1.7] mm Jean-Paul KNEIB - prospective spatial PNG

  5. R&D on optical/IR Detectors Important R&D funded by DOE for SNAP On the detectors have reached the SNAP requirements. Latest IR detector should go on the new WFPC3 camera to be installed on HST during SM4. Jean-Paul KNEIB - prospective spatial PNG

  6. Pupil & slit mirror Prism Slicer Collimator Detector Camera Entrance point SNAP IFU slicer spectrometer • IFU concept based on slicer • Compact and light (20x30x10 cm) • Spectroscopy of SN and host in the same time • Photometric calibration • Spectro-z for photo-z calibration • Demonstrator being developed at LAM IR path Jean-Paul KNEIB - prospective spatial PNG

  7. The SNAP-L Mission SNAP-L is a dedicated mission to measure Dark Energy with SuperNovae and WL measurements (and possibly Baryon Acoustic Oscillation). SNAP-L will have a deep survey and a wide survey Both dedicated for SN and WL observation strategy but both useful for « other sciences » • Key advantages of SNAP-L: • PSF, image quality, stable photometry • Wide field, Depth, • Large wavelength coverage (both in visible and NIR with 9 filters), • on board spectrograph. Jean-Paul KNEIB - prospective spatial PNG

  8. D = 8 m q = 0.3” D = 2 m q = l/D Why going in space? • 0.1” angular resolution over wide field (0.7 sq.degree) • Near-infrared unfettered by atmospheric emission/absorption • Continuous, year-round observation of selected fields • Stability! Jean-Paul KNEIB - prospective spatial PNG

  9. Space-based imaging vs ground GEMS COMBO-17 (Brown et al. 2003) Space-based imaging has a significantly higher surface density of resolved sources, which can probe the matter density power spectrum at higher redshifts than will ever be feasible from the ground. ~ 100 galaxies per sq arcmin ~ 35 galaxies per sq arcmin Jean-Paul KNEIB - prospective spatial PNG

  10. SNAP Surveys Survey Area(sq.deg) Depth(AB mag) ngal(arcmin-2) Ngal Deep/SNe 10 30.4 250 107 Wide /WL 1000=>4000 28.1 100 108.5 Panoramic 7000-10000 26.7 40-50 109 Point Source - 3 Jean-Paul KNEIB - prospective spatial PNG

  11. SNAP Deep Survey Hubble Deep Field • Base SNAP survey: 7.5 square degrees near North ecliptic pole • ~3000x as large as ACS UDF to mAB=30.4 in nine optical and IR bands. • Provides ~150 epochs over 22 months (each to mAB=27.8) for time domain studies in all nine bands [SNe, AGNs] GOODS Survey area Jean-Paul KNEIB - prospective spatial PNG

  12. SNe Systematic Control SNe observation strategy: Goal: Observe 2000 hig-redshift SN in photometry and spectroscopy up to z~1.7 How: 22-month survey covering 7.5 sq.degree, with 2400s exposure per field every 4 days. The 9 band photometry will allow to select SN candidates for spectroscopy, and ensure quality rest-frame photometry. 40% of the time is reserved for on-board spectroscopy, with a large fraction for z>1 SNe. SN redshift determine through the SiII broad line. NICMOS on HST has shown that spectro-photometry calibration can achieve better than 1% error Jean-Paul KNEIB - prospective spatial PNG

  13. SNAP Wide Area Survey • ~1000 sq.deg. ‘wide’ survey the deep field, but discussion for extension to 4000 sq.deg. • Roughly 1 year for 1000°2 of observing time • Four dithered 500 second exposures at each location; sensitive to mAB=28.1 (point source) • Every field observed in all nine optical NIR filters Hubble Deep Field Jean-Paul KNEIB - prospective spatial PNG GOODS Survey area

  14. WL 2-points stat: What is measured? <g2>~0.01 82 1.6 zs1.4 q-(n+2)/2 • Mass power spectrum normalisation • Slope of the power spectrum • Mean density parameter • Redshift of the sources • Ultimately Dark Energy constraints Jean-Paul KNEIB - prospective spatial PNG

  15. Lensing Mass Map 3D Mapping of the mass distribution. COSMOS field as an example. • green countours: • X-ray • Color blobs: • optical/phot-z • detection Jean-Paul KNEIB - prospective spatial PNG

  16. Ground/Space comparison • Shear Calibration error estimate for a constant PSF : • Ground 0.7’’ • Space 0.1’’ m: is calibrated with ‘realistic’ image simulation m~5e-3. m depends on PSF stability and ellipticity Jean-Paul KNEIB - prospective spatial PNG Waerbeke et al

  17. Ground/Space Comparison • A space 4k sq.deg survey, is equivalent to a ground 20k sq. deg survey for similar photo-z bias. • Space photo-z bias should ~5 times better, a factor of 3 improvement in the FOM Jean-Paul KNEIB - prospective spatial PNG

  18. Photometric Redshift NIR Filters are crucial for photo-z accuracy and to reduce catastrophic failures (see Ilbert et al 2006) Filter optimisation for photo-z in progress, possibility to include “U-band” filter. Jean-Paul KNEIB - prospective spatial PNG

  19. The standard method -Results Ilbert et al 2006 CFHT-LS deep field photo-z show that SED templates needs to be optimized !!! Jean-Paul KNEIB - prospective spatial PNG

  20. Calibration - template optimization CFHT-LS optimize 4 templates with 2800 spectroscopic z Need of spectro-z Calibration. On-board spectrograph can measure redshift in parallel of the SN and WL survey (~50 000 spectro-z per year of WL observation AB<24.5) Optimized templates Initial templates Jean-Paul KNEIB - prospective spatial PNG

  21. Calibration - improvement Calibration method is successful to remove systematics. More spectro-z the better, feasibility is on progress but is looking good. Jean-Paul KNEIB - prospective spatial PNG

  22. Dark Energy Constraints Produce Good photo z Use 3 WL Methods Very powerful Jean-Paul KNEIB - prospective spatial PNG

  23. Dark energy: SNII Galaxy clustering / baryon oscillations Galaxy clusters and their clustering Strong lensing Correlation with other surveys ISW, SZ, dark baryons Non-dark energy science Galaxy evolution Quasars and AGN Solar system objects Nearby galaxies, structure, stellar pops, globular clusters High-z objects MW structure + stars what SNAP can also Jean-Paul KNEIB - prospective spatial PNG

  24. Cabanac et al 2006 Strong Lensing with SNAP-L Current example: SL2S: automatic search through the CFHT-LS for arcs and partial rings around elliptical galaxies (~40 candidates out of the first 28 sq.degree) + Follow-up with an ACS snapshot program. COSMOS: 1.5 strong lenses in 1.7 sq deg. => ~10-40 thousands strong lensing system in SNAP-L WL survey. Jean-Paul KNEIB - prospective spatial PNG

  25. Marshall et al 2006 Jean-Paul KNEIB - prospective spatial PNG

  26. ACS/grism, Keck/LRIS & VLT/FORS2 observations confirm z=5.83 UDF Can see Galaxies at z~6 And has candidates up to z~8 - similarly SNAP-L will image these distant galaxies … Jean-Paul KNEIB - prospective spatial PNG

  27. High-z galaxies Stiavelli et al 2004 Expect ~100 000 z>7 galaxies in the SNAP-L SN surveys down to AB~29. Unique way to map large scale structure at z>7 (faster than JWST) and find rare objects (QSOs, strong lenses, …) SNAP-L can be seen as a survey telescope for JWST. Jean-Paul KNEIB - prospective spatial PNG

  28. Probing the end of dark ages Xiaohui Fan • z~3 quasars: 200 – 400 per sq. deg • Hundreds of z~6 quasars • Maybe 10 luminous quasars at z = 9 – 10? Jean-Paul KNEIB - prospective spatial PNG

  29. Conclusion • SNAP is a well advanced concept (R&D well advanced and ready for integration) currently proposed in the NASA JDEM context, but JDEM contract is being re-discussed for an early launch (goal 2014). • SNAP is dedicated to dark energy and will provide at least 2 surveys (AB=30,28 point sources) for SN and WL but these can address many other sciences. • France (CNES) through the spectrograph contribution is well involved, and other participation might be possible to become a stronger partner (telescope, WL data center and analysis …) Jean-Paul KNEIB - prospective spatial PNG

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