The SNAP Project at SLAC
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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

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The snap project at slac

The SNAP Project at SLAC

Phil Marshall

SLAC/KIPAC

Slide 1


The snap project at slac

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


The snap project at slac

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


The snap project at slac

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


The snap project at slac

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 project at slac

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


The snap project at slac

SNAP @ SLAC: hardware

Lead institution for development of Instrument Control Unit (ICU)

Slide 7


The snap project at slac

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


The snap project at slac

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


The snap project at slac

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


The snap project at slac

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


The snap project at slac

Slide title – Garamond 40

Elliptical galaxy lens galaxies with achromatic residuals

HST resolution: galaxy sources

Slide 12


The snap project at slac

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


The snap project at slac

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


The snap project at slac

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


The snap project at slac

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


The snap project at slac

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


The snap project at slac

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


The snap project at slac

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


The snap project at slac

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 20


The snap project at slac

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 21


The snap project at slac

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


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