LSST and JDEM as Complementary LSST and JDEM as Complementary Probes of Dark Energy 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
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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,
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LSST and JDEM as LSST and JDEM as Complementary Probes of Dark Complementary Probes of Dark
EnergyEnergy
JDEM SCG TeleconNovember 25, 2008
Tony Tyson, Andy Connolly, Zeljko Ivezic, James Jee, Steve Kahn, Sam Schmidt, Don Sweeney, Dave Wittman, Hu Zhan
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OutlineOutline
Science drivers Hardware implementation Systematics Simulations Synergy with JDEM
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• 4 billion galaxies with redshifts4 billion galaxies with redshifts• Time domain: Time domain: 1 million supernovae1 million supernovae 1 million galaxy lenses1 million galaxy lenses 5 million asteroids5 million asteroids new phenomenanew phenomena
LSST survey of 20,000 sq LSST survey of 20,000 sq degdeg
Key LSST Mission: Dark Key LSST Mission: Dark EnergyEnergy
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
Get correction vector by solving Normal equation. (A: sensitive matrix, f0: error vector.)
x
* Tools used for simulations and calculations: Zemax Matlab
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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 aZernike expansion to simulate the possible residualcontrol system errors each mirror can have an arbitrary amplitudecode goes up to 5th order polynomials
Joint analysis of WL & BAO is less affected by the systematicsJoint analysis of WL & BAO is less affected by the systematics
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Critical IssuesCritical Issues
WL shear reconstruction errors Show control to better than required precision Show control to better than required precision
using existing new facilitiesusing existing new facilities Photometric redshift errors
Develop robust photo-z calibration planDevelop robust photo-z calibration plan Undertake world campaign for spectroscopyUndertake world campaign for spectroscopy ()
Photometry errors Develop and test precision flux calibration Develop and test precision flux calibration
Cosmic shear signalTest 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
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HST ACS dataLSST:LSST:
Gold sample:Gold sample:4 billion galaxies 4 billion galaxies i<25 (S/N=25), i<25 (S/N=25), out of 10 billion out of 10 billion detected. detected. 56/sq.arcmin56/sq.arcmin
~40 galaxies~40 galaxiesper sq.arcmin per sq.arcmin used for WLused for WL
Galaxy residual shear Galaxy residual shear error is shape shot error is shape shot noise dominated.noise dominated.Averages down like Averages down like 1/N fields to the 1/N fields to the systematic floor.systematic floor.
Survey of 20,000 Survey of 20,000 sq.deg will have N ~ sq.deg will have N ~ 2000 fields in each 2000 fields in each red band r, i, z red band r, i, z
Single 10 sq.deg field full depth
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DM Pipelines
Solar System
Cosmology
Defects
MilkywayExtended Sources
Transients
Base Catalog
All Sky Database
Instance CatalogGeneration
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 SIMULATIONSIMAGE SIMULATIONS
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Input catalog for Input catalog for simulationssimulations
Millennium SimulationsKitzbichler and White (2006)
o 6 fields, 1.4x1.4 deg per fieldo 6x106 source per catalogo Based on Croton et al (2006)
and De Lucia and Blaizot (2006) models
o r<26 magnitude limito z<4 redshift limit o BVRIK Johnson and griz SDSSo Estimated u and y passbandso Type and size included
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, ~104 galaxies per unit z. Newman 2008
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Combining four LSST Combining four LSST probesprobes
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Testing more general DE modelsTesting more general DE models
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Probe anisotropyProbe anisotropy
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multiple probes of dark energymultiple 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, 2sky coverage: anisotropy? 3x109 galaxies, 106 SNe• probe growth(z) and d(z) separately• multiply lensed AGNs and SNe
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
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JDEM+LSSTJDEM+LSST
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JDEM-LSST PrioritiesJDEM-LSST Priorities
1.1. Two IR bands from space. Deep, wide. Helps Two IR bands from space. Deep, wide. Helps photo-z plus lots of astronomy (galaxy evolution, photo-z plus lots of astronomy (galaxy evolution, stellar)stellar)
2.2. JDEM spectroscopic BAO complements LSST 2-D JDEM spectroscopic BAO complements LSST 2-D BAOBAO
3.3. JDEM coverage of same 20,000 sq.deg (see #1) JDEM coverage of same 20,000 sq.deg (see #1)
4.4. Four near IR bands from space, closing the zY Four near IR bands from space, closing the zY gapgap
5.5. JDEM WL coverage of some of LSST’s survey JDEM WL coverage of some of LSST’s survey areaarea
Need quantitative modeling for joint design mission. It will Need quantitative modeling for joint design mission. It will be useful to simulate the increase in FoM for each prioritybe useful to simulate the increase in FoM for each priority
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extra slides
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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
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WL shear power spectrum and statistical WL shear power spectrum and statistical errorserrors
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
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Trade with depth and systematicsTrade with depth and systematics
LSST only
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Comparing HST with SubaruComparing HST with Subaru
ACS: 34 min (1 orbit)PSF: 0.1 arcsec (FWHM)
2 arcmin
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Comparing HST with SubaruComparing HST with Subaru
Suprime-Cam: 20 minPSF: 0.52 arcsec (FWHM)
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Galaxy ellipticity systematics in the SRDGalaxy 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