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

LSST SurveyLSST Survey

6-band Survey: ugrizy 320–1100 nm Frequent revisits: grizy

Sky area covered: >20,000 deg2 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

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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

(complementary to JDEM) Probe anisotropy

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3200 megapixel camera3200 megapixel camera

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LSST six color systemLSST six color system

Wavelength (nm)

Re

lati

ve

sy

ste

m t

hro

ug

hp

ut

(%) Includes sensor QE, atmospheric

attenuation, optical transmission functions

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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 plane2d

40 mm

Sci CCD

The LSST Focal PlaneThe LSST Focal Plane

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LSST reconstruction pipeline simulatorLSST reconstruction pipeline simulator

Perturbations

Get intra and extra focal image intensities.

I1

I2

WCS processing: get the perturbation wavefronts

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212 1

II

II

zW

0

n

Wedge

oTT

i fAAAx 1)(ix

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

Perturbation spectrum

e.g. Mirror Defocus

Active opticsActive optics

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FWHM Allocation & Budget meets SRD FWHM Allocation & Budget meets SRD RequirementsRequirements

Some TelescopeThermal Effects Included

No Explicit Camera AllocationFor Thermal Effects

Margin available

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The LSST CCD SensorThe LSST CCD Sensor

16 segments/CCD200 CCDs total3200 Total Outputs

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Flatness metrologyFlatness metrology

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The LSST site in ChileThe LSST site in Chile

photometriccalibration telescope

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Seeing distributionSeeing distribution

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There are 24 LSSTC US Institutional There are 24 LSSTC US Institutional MembersMembers

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, PrivateFunding: Public-Private Partnership NSF, DOE, Private

+ IN2P3 in France

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LSST imaging & operations simulationsLSST imaging & operations simulations

Sheared HDF raytraced + perturbation + atmosphere + wind + optics + pixel

LSST Operations, including real weather data: coverage + depth

Performance verification using Subaru imagingPerformance verification using Subaru imaging

Figure : Visits numbers per field for the 10 year simulated survey

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10-year simulation:10-year simulation: limiting magnitudes per 30s visit in limiting magnitudes per 30s visit in

main surveymain survey1 visit = 2 x 15 sec exposures1 visit = 2 x 15 sec exposures

Opsim5.72 Nov 2008

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10-year simulation:10-year simulation: number of visits per band in main number of visits per band in main

surveysurvey

Opsim5.72 Nov 2008

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LSST and Cosmic ShearLSST and Cosmic Shear

Ten redshift bins yield 55 auto and cross spectra

+ higher order

useful rangeuseful rangebaryonsbaryons

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2-D Baryon Acoustic 2-D Baryon Acoustic OscillationsOscillations

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LSST Precision on Dark Energy [in DETF LSST Precision on Dark Energy [in DETF language]language]

Combining techniques breaks degeneracies.Combining techniques breaks degeneracies.

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

techniquetechnique

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Residual shear correlationResidual shear correlation

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

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residual galaxy shear correlationresidual galaxy shear correlation

Simulation of 0.6” seeing.J. Jee 2008

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

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Photo-z SimulationsPhoto-z Simulations

Abdalla etal. 2008J=23.4 10 sigma

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Calibrating photometric Calibrating photometric redshifts 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, ~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

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JDEM-LSST JDEM-LSST ComplementarityComplementarity

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

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DETF FoM vs Etendue-TimeDETF FoM vs Etendue-Time

CombinedCombinedSeparate DE Probes

JDEM+LSST will be even better