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

20 Nov 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.

20 Nov 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

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

20 Nov 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.

20 Nov Jean-Paul KNEIB - prospective spatial PNG 6 SNAP IFU slicer spectrometer IR path Entrance point Pupil & slit mirror Slicer Prism Detector Camera Collimat or VisibleIR Wavelength coverage (  m) Field of view 3.0"  6.0" Spectral resolution,  Spatial resolution element (arc sec) 0.15 detectors LBL CCD 10  m HgCdTe 18  m Efficiency with OTA and QE>50%>40% 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

20 Nov 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.

20 Nov Jean-Paul KNEIB - prospective spatial PNG 8 Why going in space? D = 2 m  = /D D = 8 m  = 0.3 ” 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!

20 Nov Jean-Paul KNEIB - prospective spatial PNG 9 Space-based imaging vs ground 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. GEMSCOMBO-17 (Brown et al. 2003) ~ 100 galaxies per sq arcmin~ 35 galaxies per sq arcmin

20 Nov Jean-Paul KNEIB - prospective spatial PNG 10 Survey Area(sq.deg) Depth(AB mag) n gal (arcmin -2 ) N gal Deep/SNe Wide /WL 1000=> Panoramic SNAP Surveys Point Source - 3 

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

20 Nov 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

20 Nov 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 m AB =28.1 (point source)  Every field observed in all nine optical NIR filters GOODS Survey area Hubble Deep Field

20 Nov Jean-Paul KNEIB - prospective spatial PNG 14 WL 2-points stat: What is measured? Mass power spectrum normalisation Mass power spectrum normalisation Slope of the power spectrum Slope of the power spectrum Mean density parameter Mean density parameter Redshift of the sources Redshift of the sources Ultimately Dark Energy constraints Ultimately Dark Energy constraints ~0.01  8 2  1.6 z s 1.4 q -(n+2)/2 ~0.01  8 2  1.6 z s 1.4 q -(n+2)/2

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

20 Nov 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 Waerbeke et al

20 Nov Jean-Paul KNEIB - prospective spatial PNG 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

20 Nov 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.

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

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

20 Nov 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.

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

20 Nov Jean-Paul KNEIB - prospective spatial PNG 23 what SNAP can also  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

20 Nov Jean-Paul KNEIB - prospective spatial PNG 24 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. Cabanac et al 2006

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

20 Nov 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 …

20 Nov Jean-Paul KNEIB - prospective spatial PNG 27 High-z galaxies Stiavelli et al 2004 Expect ~ 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.

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

20 Nov 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 …)