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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<ul><li><p>LSST and JDEM as Complementary Probes of Dark EnergyJDEM SCG TeleconNovember 25, 2008Tony Tyson, Andy Connolly, Zeljko Ivezic, James Jee, Steve Kahn, Sam Schmidt, Don Sweeney, Dave Wittman, Hu Zhan </p></li><li><p>OutlineScience driversHardware implementationSystematicsSimulationsSynergy with JDEM</p></li><li><p> 4 billion galaxies with redshifts Time domain: 1 million supernovae 1 million galaxy lenses 5 million asteroids new phenomenaLSST survey of 20,000 sq deg</p></li><li><p>LSST Survey 6-band Survey: ugrizy 3201100 nm Frequent revisits: grizy</p><p> Sky area covered: &gt;20,000 deg2 0.2 arcsec / pixel</p><p> Each 10 sq.deg field reimaged ~2000 times</p><p> Limiting magnitude: 27.6 AB magnitude @5s 25 AB mag /visit = 2x15 seconds Photometry precision: 0.005 mag requirement 0.003 mag goal</p></li><li><p>Key LSST Mission: Dark EnergyPrecision measurements of all dark energy signatures in a single data set. Separately measure geometry and growth of dark matter structure vs cosmic time. </p><p> 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</p></li><li><p>3200 megapixel camera</p></li><li><p>LSST six color systemWavelength (nm)Relative system throughput (%)Includes sensor QE, atmospheric attenuation, optical transmission functions</p></li><li><p>Wavefront Sensor LayoutGuide Sensors (8 locations)Wavefront Sensors (4 locations)3.5 degree Field of View (634 mm diameter)Curvature Sensor Side View ConfigurationThe LSST Focal Plane</p></li><li><p>LSST reconstruction pipeline simulatorPerturbations Get correction vector by solving Normal equation. (A: sensitive matrix, f0: error vector.)</p></li><li><p>Correct for perturbations due to thermal and mechanical distortionsEach 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 polynomialsPerturbation spectrume.g. Mirror DefocusActive optics</p></li><li><p>FWHM Allocation &amp; Budget meets SRD RequirementsSome TelescopeThermal Effects IncludedNo Explicit Camera AllocationFor Thermal EffectsMargin available </p></li><li><p>The LSST CCD Sensor16 segments/CCD 200 CCDs total 3200 Total Outputs</p></li><li><p>Flatness metrology</p></li><li><p>The LSST site in Chile photometriccalibration telescope</p></li><li><p>Seeing distribution</p></li><li><p>There are 24 LSSTC US Institutional MembersBrookhaven National Laboratory California Institute of TechnologyCarnegie Mellon UniversityColumbia UniversityGoogle Inc. Harvard-Smithsonian Center for Astrophysics Johns Hopkins University Las Cumbres Observatory Lawrence Livermore National Laboratory National Optical Astronomy ObservatoryPrinceton UniversityPurdue University</p><p>Research Corporation Rutgers University Stanford Linear Accelerator Center Stanford University KIPAC The Pennsylvania State UniversityUniversity of Arizona University of California, DavisUniversity of California, Irvine University of Illinois at Champaign-Urbana University of PennsylvaniaUniversity of PittsburghUniversity of WashingtonFunding: Public-Private Partnership NSF, DOE, Private+ IN2P3 in France</p></li><li><p>LSST imaging &amp; operations simulationsSheared HDF raytraced + perturbation + atmosphere + wind + optics + pixel LSST Operations, including real weather data: coverage + depth Performance verification using Subaru imaging</p></li><li><p>10-year simulation: limiting magnitudes per 30s visit in main survey1 visit = 2 x 15 sec exposuresOpsim5.72 Nov 2008</p></li><li><p>10-year simulation: number of visits per band in main surveyOpsim5.72 Nov 2008</p></li><li><p>LSST and Cosmic ShearTen redshift bins yield 55 auto and cross spectra+ higher orderuseful rangebaryons</p></li><li><p>2-D Baryon Acoustic Oscillations</p></li><li><p>LSST Precision on Dark Energy [in DETF language] Combining techniques breaks degeneracies.Joint analysis of WL &amp; BAO is less affected by the systematics </p></li><li><p>Critical IssuesWL shear reconstruction errorsShow control to better than required precision using existing new facilities Photometric redshift errorsDevelop robust photo-z calibration plan Undertake world campaign for spectroscopy ()Photometry errors Develop and test precision flux calibration technique </p></li><li><p>Residual shear correlationCosmic 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.</p><p>Compare with expected cosmic shear signal.</p><p>Conclusion: 200 exposures per sky patch will yield negligible PSF induced shear systematics. Wittman (2005) Stars</p></li><li><p>HST ACS dataLSST:</p><p>Gold sample:4 billion galaxies i</p></li><li><p>residual galaxy shear correlation</p><p>Simulation of 0.6 seeing.J. Jee 2008Galaxy residual shear error is shape shot noise dominated.Averages down like 1/N fields to the systematic floor.</p><p>Survey of 20,000 sq.deg will have N ~ 2000 fields in each red band r, i, z Single 10 sq.deg field full depth</p></li><li><p>DM PipelinesSolar SystemCosmologyDefectsMilkywayExtended SourcesTransientsBase CatalogAll Sky DatabaseInstance CatalogGenerationGenerate the seed catalog as required for simulation. Includes: Metadata Size PositionOperation Simulation Type VariabilitySource Image GenerationColor Brightness Proper motionIntroduce shear parameter from cosmology metadata DM Data base load simulationGenerate per FOVPhoton PropagationOperation Simulation AtmosphereTelescopeCameraDefectsFormattingGenerate per SensorCalibration Simulation LSST Sample Images and CatalogsIMAGE SIMULATIONS</p></li><li>Input catalog for simulationsMillennium SimulationsKitzbichler and White (2006)6 fields, 1.4x1.4 deg per field6x106 source per catalogBased on Croton et al (2006) and De Lucia and Blaizot (2006) modelsr</li><li><p>Photo-z SimulationsAbdalla etal. 2008J=23.4 10 sigma</p></li><li><p>Calibrating photometric 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</p></li><li><p>Combining four LSST probes</p></li><li><p>Testing more general DE models</p></li><li><p>Probe anisotropy</p></li><li>multiple 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</li><li><p>JDEM-LSST Complementarity JDEM+LSST in 20,000 sq.deg and in fifty 10 sq.deg deep drilling fields</p><p>Estimated cosmological constraints using LSST+JDEM</p><p>Optimum strategy for joint DE mission risk reduction </p><p>Priorities for max complementarity and cost effectiveness </p></li><li><p>JDEM+LSST</p></li><li><p>JDEM-LSST Priorities Two IR bands from space. Deep, wide. Helps photo-z plus lots of astronomy (galaxy evolution, stellar) JDEM spectroscopic BAO complements LSST 2-D BAO JDEM coverage of same 20,000 sq.deg (see #1) Four near IR bands from space, closing the zY gap JDEM WL coverage of some of LSSTs survey area</p><p> Need quantitative modeling for joint design mission. It will be useful to simulate the increase in FoM for each priority</p></li><li><p>extra slides</p></li><li><p>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 </p></li><li><p>WL shear power spectrum and statistical errorsSignalNoiseSNAPLSSTgastrophysicsLSST: fsky = 0.5, ng = 40 SNAP: fsky = 0.1, ng =100 </p><p>RMS intrinsic contribution to the shear g= 0.25 (conservative). </p><p>No systematics!</p><p>Jain, Jarvis, and Bernstein 2006</p></li><li><p>Trade with depth and systematicsLSST only</p></li><li><p>Comparing HST with Subaru</p></li><li><p>Comparing HST with Subaru</p></li><li><p>Galaxy ellipticity systematics in the SRDSpecification: 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</p></li><li><p>DETF FoM vs Etendue-TimeCombinedSeparate DE ProbesJDEM+LSST will be even better</p><p>The 8.4m LSST primary-tertiary mirror blank, after successful casting in March 2008. Two concentric mirrors (the 8.4m diameter primary and the 5m diameter tertiary) will be polished into the surface over the next two years.*Most allocations are met by the specifications for the reference design. Tension exists between r-band and i-band image quality and Y-band, causing the sensor FWHM spec to miss its allocation.</p></li></ul>