1. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory The Super/Nova Acceleration Probe (SNAP) Natalia Kuznetsova Natalia Kuznetsova Lawrence Berkeley National Lab Cosmo06 September 24 - 29, 2006 Tahoe City, CA

2. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory SNAP 101 Space-based 2-m class telescope dedicated to performing precision measurements of the dark energy equation of state parameter w through: –A wide field lensing survey –Discovery and follow-up of ~2,000 type Ia supernovae SNAP will be very data-rich, producing data useful not only for precision cosmology studies, but for many other applications 2

3. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory Focal plane Fixed filters atop the sensors VisibleNIR Integral Field Spectrograph (3”x3”) 3 Spectrograph port

4. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory Physics with SNAP: Deep & Large Space Surveys The SNAP surveys will have an unprecedented combination of depth, solid- angle, angular resolution, temporal sampling, and wavelength  coverage Hubble Deep Fields illustrate the impact of a deep space survey. SNAP SN survey 5,000 x HDF. –SNAP m AB = 27.7 per filter (30.4 co-added) every 4 days SNAP lensing survey ~10 6 x HDF, 500 x COSMOS! –m AB = 28.1 co-added GOODS HDF COSMOS SNAP Deep Survey Area SNAP Lensing Survey Area 4

5. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory Physics With SNAP: Supernovae SNAP ‘s homogeneous SN dataset over the redshift range up to z = 1.7 will have carefully controlled systematics –The quality, not the quantity, of SN observations is the primary factor for dark energy accuracy –SNAP will have photometric measurements of ~2,000 type Ia SN in 9 broadband filters, as well as their spectra at maximum light 5 ~2000 SNe Ia DE discovery redshift z

6. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory Physics with SNAP: Weak Lensing Weak lensing (WL) provides an independent and complementary measurement of cosmological parameters Space-based WL measurements are particularly helpful at small scales, where the shot noise is small due to the large surface density of resolved galaxies 6 ground (0.7” seeing) space (0.12”) Courtesy Jason Rhodes

7. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory Ancillary Science From SNAP Galaxy structure formation Galaxy clusters Gamma-ray burst afterglows Reionization history Transients/variables Stars Solar system objects Strong gravitational lensing …. 7

8. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory Simulating a Dark Energy Mission We have created a sophisticated simulation that allows one to simulate a dark energy mission (space- or ground- based) It is a collaborative project written in object-oriented Java Basis for future data processing pipeline 8

9. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory Studies with SNAPsim SNAPsim is easily configurable for studying various choices of mission parameters Examples of studies done using SNAPsim include: –SNAP exposure time - cadence trade study –SNAP detector-noise requirements –Calibration error propagation –Spectroscopic measurement requirements –Alternative instrumentation suites –SNAP primary aperture trade study –Ground-based missions –SNAP telescope blur requirements –Weak gravitational lensing mission simulation 9

10. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory SNAPsim Physics Type Ia, II supernova spectra, varying stretch Zodiacal background Cardelli-Clayton-Mathis model dust Atmosphere effects for ground-based missions Sophisticated fitting algorithms for lightcurve and cosmology fitting 10 Simulated and fitted lightcurves for a type Ia SN at z = 1.7 filter 7filter 8filter 9

11. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory Lightcurve Redshift Series NIR Bands Rest frame V Rest frame B Z = 0.8Z = 1.2Z = 1.6 Optical Bands 11

12. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory Extracting Cosmology The final step of the simulation is extracting the cosmological parameters The plot is an example of the cosmology to be obtained from SNAP results only (no CMB priors) courtesy Eric Linder 12

13. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory NIR Detector R&D SNAPsim is used extensively for SNAP’s instrumentation and R&D work –For example, a recent study has investigated the effect of varying NIR detector parameters on the output physics The idea is to find out what combination of detector specs (dark current, read noise, quantum efficiency) produces optimal science at the lowest cost 13 Infrared Sensors  Error Contours courtesy Matt Brown Total Noise (e) QE

14. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory IR Detector Trade-Off Study (2)  error vs. redshift for visible only and visible + NIR detectors Matt Brown et al., proc. of 2006 SPIE symposium on Astronomical Telescopes and Instrumentation 14

15. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory Simulating a Ground-Based Observatory SNAPsim is also capable of simulating a ground-based observatory As an example, we simulate a somewhat idealized 8-m class telescope in the Southern hemisphere, with NIR detectors We then look at the lightcurves for z = 1.2 and z = 1.4 supernovae for a GOODS South target and an equatorial pole one Natalia Kuznetsova, Larry Gladney, Alex Kim Atmosphere transmission Atmosphere emission 15

16. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory Simulating a Ground-Based Observatory (2) Examples: a (somewhat) idealized 8-m ground telescope (with IR), observing a target in the GOODS South field and an equatorial one –Equatorial pole target gets a worse S/N, but there are no “holes” in the lightcurve GOODS South targetEquatorial pole target 16

17. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory Spectrograph Simulation Pixel-level simulation using shapelets to create fake spectra of both point and extended objects 17 Point source y courtesy Richard Massey

18. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory Host galaxy spectrum Spectrograph Simulation (2) y SN spectrum Same magnitude SN and galaxy; no noise Reconstructed SN spectrum (z = 1.7) 18 (a few slices from slicer mirror) courtesy Alain Bonissent

19. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory Pixel Scale for Weak Lensing Also using shapelets to simulate space-based, pixel- level images Initial result: SNAP nominal pixel scale of 0.10 arcsec/pixel is in the optimal well –This pixel scale is optimal for both supernova and weak lensing studies Contribution of intrinsic shear variance to the weak lensing power spectrum error 19 SNAP nominal courtesy Will High

20. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory Self Calibration in Supernova Surveys Filter zeropoint uncertainties affect precision of cosmological parameters. Fitting for all SN distance moduli  simultaneously allows for a degree of self calibration which yields a noticeable improvement in the final precision (Kim & Miquel, Astropart. Phys. 24 (2006), 451). We show this effect by simulating an SNLS-like survey and comparing the results against the usual SN by SN fit; we fit for  M ) with w=-1. courtesy Lorenzo Faccioli; also see poster in hallway 20

21. September 22, 2006 Natalia Kuznetsova Lawrence Berkeley National Laboratory Conclusions SNAP is specifically targeted at controlling systematic uncertainties Our sophisticated mission simulation, SNAPsim, enables us to pursue such a tight control of errors –Numerous R & D, trade-off, and physics studies in progress, not only those presented in this talk For more info, please go to http://snap.lbl.gov 21