1. LSST and JDEM as Complementary Probes of Dark Energy JDEM SCG Telecon November 25, 2008 Tony Tyson, Andy Connolly, Zeljko Ivezic, James Jee, Steve Kahn, Sam Schmidt, Don Sweeney, Dave Wittman, Hu Zhan

2. 2 Outline  Science drivers  Hardware implementation  Systematics  Simulations  Synergy with JDEM

3. 3 4 billion galaxies with redshifts 4 billion galaxies with redshifts Time domain: Time domain: 1 million supernovae 1 million supernovae 1 million galaxy lenses 1 million galaxy lenses 5 million asteroids 5 million asteroids new phenomena new phenomena LSST survey of 20,000 sq deg

4. LSST Survey  6-band Survey: ugrizy 320–1100 nm Frequent revisits: grizy  Sky area covered: >20,000 deg 2 0.2 arcsec / pixel  Each 10 sq.deg field reimaged ~2000 times  Limiting magnitude: 27.6 AB magnitude @5  25 AB mag /visit = 2x15 seconds  Photometry precision: 0.005 mag requirement 0.003 mag goal

5. 5 Key LSST Mission: Dark Energy Precision measurements of all dark energy signatures in a single data set. Separately measure geometry and growth of dark matter structure vs cosmic time.  Weak gravitational lensing correlations (multiple lensing probes!)  Baryon acoustic oscillations (BAO)  Counts of dark matter clusters  Supernovae to redshift 0.8 (complementary to JDEM)  Probe anisotropy

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9. 9 3200 megapixel camera

10. 10 LSST six color system Wavelength (nm) Relative system throughput (%) Includes sensor QE, atmospheric attenuation, optical transmission functions

11. 11 Wavefront Sensor Layout Guide Sensors (8 locations) Wavefront Sensors (4 locations) 3.5 degree Field of View (634 mm diameter) Curvature Sensor Side View Configuration Focal plane 2d 40 mm Sci CCD The LSST Focal Plane

12. 12 LSST reconstruction pipeline simulator Perturbations Get intra and extra focal image intensities. I1I1 I2I2 WCS processing: get the perturbation wavefronts Get correction vector by solving Normal equation. ( A : sensitive matrix, f 0 : error vector.) * Tools used for simulations and calculations: Zemax Matlab

13. 13 Correct for perturbations due to thermal and mechanical distortions Each optic has 6 dof (decenter, defocus, three euler angles) Perturbations are placed on the three mirrors using a Zernike expansion to simulate the possible residual control system errors each mirror can have an arbitrary amplitude code goes up to 5th order polynomials Perturbation spectrum e.g. Mirror Defocus Active optics

14. 14 FWHM Allocation & Budget meets SRD Requirements Some Telescope Thermal Effects Included No Explicit Camera Allocation For Thermal Effects Margin available

15. 15 The LSST CCD Sensor 16 segments/CCD 200 CCDs total 3200 Total Outputs

16. 16 Flatness metrology

17. 17 The LSST site in Chile photometric calibration telescope

18. 18 Seeing distribution

19. 19 There are 24 LSSTC US Institutional Members  Brookhaven National Laboratory  California Institute of Technology  Carnegie Mellon University  Columbia University  Google Inc.  Harvard-Smithsonian Center for Astrophysics  Johns Hopkins University  Las Cumbres Observatory  Lawrence Livermore National Laboratory  National Optical Astronomy Observatory  Princeton University  Purdue University  Research Corporation  Rutgers University  Stanford Linear Accelerator Center  Stanford University –KIPAC  The Pennsylvania State University  University of Arizona  University of California, Davis  University of California, Irvine  University of Illinois at Champaign-Urbana  University of Pennsylvania  University of Pittsburgh  University of Washington Funding: Public-Private Partnership NSF, DOE, Private + IN2P3 in France

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21. 21 LSST imaging & operations simulations Sheared HDF raytraced + perturbation + atmosphere + wind + optics + pixel LSST Operations, including real weather data: coverage + depth Performance verification using Subaru imaging Figure : Visits numbers per field for the 10 year simulated survey

22. 22 10-year simulation: limiting magnitudes per 30s visit in main survey 1 visit = 2 x 15 sec exposures Opsim5.72 Nov 2008

23. 23 10-year simulation: number of visits per band in main survey Opsim5.72 Nov 2008

24. 24 LSST and Cosmic Shear Ten redshift bins yield 55 auto and cross spectra + higher order useful range baryons

25. 25 2-D Baryon Acoustic Oscillations

26. 26 LSST Precision on Dark Energy [in DETF language] Combining techniques breaks degeneracies. Joint analysis of WL & BAO is less affected by the systematics

27. 27 Critical Issues  WL shear reconstruction errors  Show control to better than required precision using existing new facilities  Show control to better than required precision using existing new facilities  Photometric redshift errors  Develop robust photo-z calibration plan  Develop robust photo-z calibration plan  Undertake world campaign for spectroscopy  Undertake world campaign for spectroscopy ( )  Photometry errors  Develop and test precision flux calibration technique  Develop and test precision flux calibration technique

28. 28 Residual shear correlation Cosmic shear signal Test of shear systematics: Use faint stars as proxies for galaxies, and calculate the shear-shear correlation after correcting for PSF ellipticity via a different set of stars. Compare with expected cosmic shear signal. Conclusion: 200 exposures per sky patch will yield negligible PSF induced shear systematics. Wittman (2005) Stars

29. 29 HST ACS data LSST: Gold sample: 4 billion galaxies i<25 (S/N=25), out of 10 billion detected. 56/sq.arcmin ~40 galaxies per sq.arcmin used for WL

30. 30 residual galaxy shear correlation Simulation of 0.6” seeing. J. Jee 2008 Galaxy residual shear error is shape shot noise dominated. Averages down like 1/N fields to the systematic floor. Survey of 20,000 sq.deg will have N ~ 2000 fields in each red band r, i, z Single 10 sq.deg field full depth

31. 31 DM Pipelines Solar System Cosmology Defects Milkyway Extended Sources Transients Base Catalog All Sky Database Instance Catalog Generation Generate the seed catalog as required for simulation. Includes: Metadata Size Position Operation Simulation Type Variability Source Image Generation Color Brightness Proper motion Introduce shear parameter from cosmology metadata DM Data base load simulation Generate per FOV Photon Propagation Operation Simulation Atmosphere Telescope Camera Defects Formatting Generate per Sensor Calibration Simulation LSST Sample Images and Catalogs IMAGE SIMULATIONS

32. 32 Input catalog for simulations  Millennium Simulations Kitzbichler and White (2006) o 6 fields, 1.4x1.4 deg per field o 6x10 6 source per catalog o Based on Croton et al (2006) and De Lucia and Blaizot (2006) models o r<26 magnitude limit o z<4 redshift limit o BVRIK Johnson and griz SDSS o Estimated u and y passbands o Type and size included 32

33. 33 Photo-z Simulations Abdalla etal. 2008 J=23.4 10 sigma

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35. 35 Calibrating photometric redshifts Cross-correlation LSS-based techniques can reconstruct the true z distribution of a photo-z bin, even with spectroscopy of only the brightest galaxies at each z. These techniques meet LSST requirements with easily attainable spectroscopic samples, ~10 4 galaxies per unit z. Newman 2008

36. 36 Combining four LSST probes

37. 37 Testing more general DE models

38. 38 Probe anisotropy

39. 39 multiple probes of dark energy WL shear-shear tomography WL bi-spectrum tomography Distribution of 250,000 shear peaks Baryon acoustic oscillations 1 million SNe Ia, z<1 per year Low l, 2  sky coverage: anisotropy? 3x10 9 galaxies, 10 6 SNe probe growth(z) and d(z) separately multiply lensed AGNs and SNe

40. 40 JDEM-LSST Complementarity  JDEM+LSST in 20,000 sq.deg and in fifty 10 sq.deg deep drilling fields  Estimated cosmological constraints using LSST+JDEM  Optimum strategy for joint DE mission risk reduction  Priorities for max complementarity and cost effectiveness

41. 41 JDEM+LSST

42. 42 JDEM-LSST Priorities 1. Two IR bands from space. Deep, wide. Helps photo- z plus lots of astronomy (galaxy evolution, stellar) 2. JDEM spectroscopic BAO complements LSST 2-D BAO 3. JDEM coverage of same 20,000 sq.deg (see #1) 4. Four near IR bands from space, closing the zY gap 5. JDEM WL coverage of some of LSST’s survey area Need quantitative modeling for joint design mission. It will be useful to simulate the increase in FoM for each priority Need quantitative modeling for joint design mission. It will be useful to simulate the increase in FoM for each priority

43. 43 extra slides

44. 44 Requirement of integrated 50 galaxies per sq.arcminute: green line in the following plot. The corresponding 10 sigma limiting magnitudes in r and i are: r=25.6 i=25.0 AB mag

45. 45 WL shear power spectrum and statistical errors Signal Noise SNAP LSST gastrophysics LSST: fsky = 0.5, ng = 40 SNAP: fsky = 0.1, ng =100 RMS intrinsic contribution to the shear σ  = 0.25 (conservative). No systematics! Jain, Jarvis, and Bernstein 2006

46. 46 Trade with depth and systematics LSST only

47. 47 Comparing HST with Subaru

48. 48 Comparing HST with Subaru

49. 49 Galaxy ellipticity systematics in the SRD Specification: The median LSST image (two per visit) must have the median E1, E2, and Ex averaged over the FOV, less than SE3 for 1 arcmin, and less than SE4 for 5 arcmin. No more than EF2 % of images will exceed values of SE5 for 1 arcmin, nor SE6 for 5 arcmin

50. 50 DETF FoM vs Etendue-Time CombinedSeparate DE Probes JDEM+LSST will be even better