The SNAP Project at SLAC

The SNAP Project at SLAC Phil Marshall SLAC/KIPAC Slide 1

Outline KIPAC is playing an active role in the SNAP project, a strong contender for the JDEM mission • Overview of the SNAP telescope: motivation, primary science experiments, system design • Hardware development at SLAC (Kahn, Althouse, Craig, Huffer) • Strong lens survey science (Blandford, Marshall, with Baltz, Bradac and Sako) • Pre-cursor datasets: the HAGGLeS project • Summary Slide 2

Probing Dark Energy Multiple complementary experiments, allowing marginalisation over dark matter and baryonic astrophysics Measuring the distance scale with type Ia supernovae (Riess et al 2004, Aldering, KIPAC et al 2005) Slide 3

Probing Dark Energy 1 arcmin Multiple complementary experiments, allowing marginalisation over dark matter and baryonic astrophysics The distance scale with type Ia supernovae The low-redshift matter power spectrum, growth of structure and cosmic geometry with weak gravitational lensing Slide 4

Probing Dark Energy Multiple complementary experiments, allowing marginalisation over dark matter and baryonic astrophysics The distance scale with type Ia supernovae The low-redshift matter power spectrum, growth of structure and cosmic geometry with weak gravitational lensing Systematics-limited measurements Complementarity/vital cross-checking Copious ancillary science for free... Slide 5

The SNAP design 2-metre class telescope Optical and NIR imager, 0.7 square degree f.o.v. 0.13” PSF, 0.1” pixels, cf. WFPC2 9 matched, fixed filters Multi-object (IFU) spectrograph L2 orbit, dedicated telemetry base station Slide 6

SNAP @ SLAC: hardware Lead institution for development of Instrument Control Unit (ICU) Slide 7

SNAP @ SLAC: hardware NMIinstrument Instrument RouterA SBC Primary ICU FPA RouterA NMIFPA Primary Redundant DLI DLI DVI0 DVI1 DVI34 DVI35 FPA RouterB NMIFPA SBC NMIinstrument Instrument RouterB Lead institution for development of Instrument Control Unit (ICU) Network-centric approach allows greater flexibility, solves mass- memory problem, improved efficiency and throughput Slide 8

SNAP @ SLAC: hardware • Lead institution for development of Instrument Control Unit (ICU) • Also designing fine guider system: • Crucial component enables milliarcsecond pointing corrections • Guiders will be prototyped at SLAC over next year CHU#2 CHU#1 CHU#3 CHU#4 Slide 9

SNAP @ SLAC: hardware Lead institution for development of Instrument Control Unit (ICU) Flexible network-centric approach proposed Distributed memory part of scheme adopted at this stage R&D phase continues Fine guiding solution is the baseline for SNAP Prototyping over the next year as part of SNAP project technology demonstration Slide 10

SNAP @ SLAC: Science KIPAC is leading the Strong Gravitational Lensing Working Group: SNAP imaging data well matched to an idealised strong lens survey 9 filters (6 optical + 3 NIR) for SN typing and WL galaxy photo-z 0.1” angular resolution, stable PSF cf. WFPC2 on HST – but 650 times larger field of view (0.7 sq. deg.) (Aldering et al 2005) Slide 11

Slide title – Garamond 40 Elliptical galaxy lens galaxies with achromatic residuals HST resolution: galaxy sources Slide 12

Strong lens surveying In 1000 sq. deg, expect: ~20 million ellipticals ~20000 eg-g lenses ~500 eg-q lenses (cf. ~100 currently known lens systems) Initial cut (1000 to few) all important in “expert” system Lens modeling of c. 105 systems “Low resolution spectra” for redshifts and lens mass Slide 13

Science case Dark matter in elliptical galaxies: density profile (e.g. Rusin et al 2003), relation to luminous matter (e.g. Treu & Koopmans), Small-scale CDM substructure, from flux ratios (e.g. Bradac et al 2004), and image curvature (Irwin & Shmakova 2005): Redshifts of faintest galaxies / cosmography from distance ratios... Slide 14

Distance ratios Image separation is proportional to distance ratio: Extracting cosmology requires accurate knowledge of fundamental plane (and its evolution), and of the source redshifts... Slide 15

Synergy with LSST All ~20000 SNAP lenses may be monitored by LSST Supernovae in lensed galaxies make excellent features in the light curves for measuring time delays: expect c. 1600 in ten-year LSST survey, with c. 10 day time resolution Sensitivity to lens model is reduced for this subset: Figures from Goobar et al 2002 Slide 16

Life before SNAP: HAGGLeS HST archive is the precursor dataset Deep, multi-filter, high galactic latitude coverage is 2.2 sq degrees 104 elliptical galaxies, c. 25 lenses... Numbers on borderline between eyeball and automated search Slide 17

Life before SNAP: HAGGLeS HST archive is the precursor dataset Deep, multi-filter, high galactic latitude coverage is 2.2 sq degrees 104 elliptical galaxies, c. 25 lenses... Numbers on borderline between eyeball and automated search Funded as HST Archive Legacy project in April 2005 Slide 18

Life before SNAP: HAGGLeS HST archive is the precursor dataset Deep, multi-filter, high galactic latitude coverage is 2.2 sq degrees 104 elliptical galaxies, c. 25 lenses... Numbers on borderline between eyeball and automated search Funded as HST Archive Legacy project in April 2005 Pilot projects (SDSS LRGs, and UDF) underway Slide 19

Summary KIPAC is actively and enthusiastically involved in both hardware and software development for SNAP The wide survey will increase the galaxy-scale strong lens sample size by 2 orders of magnitude over the current number Statistical studies of dark matter in elliptical galaxies, the faintest source galaxies, and potentially dark energy will be possible This survey will be highly complementary to its LSST counterpart An expert system for automated lens identification is under development as part of the HAGGLeS project: new lenses will be discovered en route Slide 22

The SNAP Project at SLAC