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Catalog Simulation 1 (CatSim1) and Image Simulation 1 (ImSim1)

Catalog Simulation 1 (CatSim1) and Image Simulation 1 (ImSim1). Huan Lin Experimental Astrophysics Group Fermilab. Current CatSim1/ImSim1 Personnel. U. Chicago: Josh Frieman, Erin Sheldon, Risa Wechsler

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Catalog Simulation 1 (CatSim1) and Image Simulation 1 (ImSim1)

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  1. Catalog Simulation 1 (CatSim1) and Image Simulation 1 (ImSim1) Huan Lin Experimental Astrophysics Group Fermilab

  2. Current CatSim1/ImSim1 Personnel • U. Chicago: Josh Frieman, Erin Sheldon, Risa Wechsler • Fermilab: Jim Annis, Nickolai Kuropatkine, Huan Lin, Wyatt Merrit, Vic Scarpine, Neha Sharma, Albert Stebbins, Chris Stoughton

  3. Analysis Tests on CatSim1/ImSim1 Outputs • Galaxy and stellar catalogs: recovery of input magnitudes and colors • Photometric redshifts: bias, scatter, catastrophic errors • Galaxy clusters: tests of cluster finding algorithm (maxBCG), i.e., completeness, contamination, etc. • Weak lensing: recovery of input galaxy shapes (moments) and shears • Weak lensing: cluster-galaxy cross correlations (i.e., Johnston et al. analysis) • Angular power spectrum: recovery of simulation power spectrum

  4. CatSim1 Plan • N-body Simulation (Risa) • Hubble Volume Simulation • Cosmology: M = 0.3,  = 0.7, h=0.7, 8 = 0.9 • Sky area: 400 sq deg catalog area, with 300 sq deg subset imaging area • Location: RA = -32.0 to +1.5 deg, Dec = -45.5 to –30.0 deg, region is within “SPT overlap” area of DES • Redshift limit z = 1.4

  5. CatSim1 Plan (cont’d) • “Primary” galaxy distribution (Risa) • Galaxies drawn from Hubble Volume Simulation using Risa’s method • Galaxies down to 0.4 L* • Luminosity function model: Blanton et al. SDSS LF + passive evolution • Galaxy SEDs drawn from real SDSS galaxies, using Blanton et al. kcorrect galaxy templates (remapped to extended CWW SEDs as needed due to k-correction issues at higher redshifts) • Galaxy color-environment correlations based on the SDSS, with no redshift evolution

  6. CatSim1 Plan (cont’d) • “Background” galaxy distribution (Risa) • Galaxies distributed randomly in space and are NOT clustered • Galaxies fill in from below 0.4 L* at each redshift, down to apparent flux limit z = 24 • LF model: Blanton et al. SDSS LF + passive evolution • Galaxy SEDs drawn from real SDSS galaxies, using Blanton et al. kcorrect and extended CWW galaxy templates

  7. CatSim1 Plan (cont’d) • Galaxy shapes (Erin) • Draw shapelet coefficients from distribution for real SDSS galaxies (see Kelly & McKay) • Michigan adaptive moments for each simulated galaxy taken from the real SDSS galaxy upon which the simulated galaxy is based • Galaxy shear (Albert, Risa) • Code generates gridded shear field, using Born approximation, from the dark matter particle distribution in the Hubble Volume Simulation • Shear field resolution of about 3 arcmin, or l 1000 • Interpolate gridded shear field to determine shear at position of each simulated galaxy

  8. CatSim1 Plan (cont’d) • Stars, Extinction (Huan) • Brighter stars: actual stars from USNO-B catalog over the simulation area • Fainter stars: drawn from the Besancon stellar population synthesis model (http://bison.obs-besancon.fr/modele/) for the galaxy • Tabulate galactic extinction values from SFD at location of each simulated star and galaxy • Not included this round • Supernovae • Quasars (possibility of becoming available before ImSim1)

  9. CatSim1 Catalog Quantities • RA, Dec • Redshift • Run, rerun, camcol, field, objid of SDSS galaxy upon which simulated galaxy is based • SED type (spectral coefficients for Blanton et al. kcorrect templates) • griz absolute mags, apparent mags, galactic extinction values • Shapelet coefficients • Michigan moments (Ixx, Ixy, Iyy, rho4) • Reduced shear components, magnification • Object type flag (primary/background galaxy, USNO/model star) • Additional N-body simulation parameters (halo mass, peculiar velocity, …) that Risa deems useful

  10. ImSim1 Tools • Observing simulation code – Jim • Java-based image simulation package – Chris, Nickolai (http://home.fnal.gov/~stoughto/gov.fnal.eag/) • Optics and PSF code (from Steve Kent) – Vic

  11. ImSim1 Plan • Pointing information • Boresight, hour angle, airmass • Atmosphere (photometric zeropoints at airmass=1, extinction, seeing, sky brightness) • Telescope focus

  12. ImSim1 Plan (cont’d) • Atmosphere model • Transparency or photometric zeropoints in griz • Extinction coefficients in griz • Seeing in griz • Moffat profile PSF • Airmass0.6 and wavelength-0.2 dependence of PSF FWHM • Drawn randomly (no temporal or spatial correlations) from SuperMACHO/Mosaic-II seeing distribution from Tim Abbott • No differential refraction • Sky brightness variations in griz as for ImSim0, but also add airmass dependence

  13. ImSim1 Plan (cont’d) • Optics model • griz PSFs pre-computed on a grid of focal plane positions and for different telescope focus values (~1 PSF / 3 sq. arcmin; telescope focus resolution TBD; 5x5 points per pixel, out to 5) • Geometric distortions from the telescope+corrector optics • Geometric transformations include both linear terms (shift, rotation, scale) and nonlinear distortion terms (e.g., described by a polynomial of arbitrary order in x and y coordinates) • Pupil ghost image: do an actual fit to Steve's simulated image • No vignetting • No scattered light and no star ghosts

  14. ImSim1 Plan (cont’d) • CCD model • Take from actual LBNL devices as available, else default to ImSim0 • Gain, bias, read noise, and dark current • QE, flat fields • Bad columns • Charge diffusion • Glowing edges: model using an additional geometric transformation, one which varies quickly at the CCD edges • Saturated objects, bleeding columns: saturation/readout model

  15. ImSim1 Plan (cont’d) • Astronomical object model • Stars from CatSim1 • Galaxies from CatSim1 • Rendered from shapelet coefficients supplied by CatSim1 • Apply shears and magnifications specified by CatSim1 • Poisson noise added to magnitudes supplied by CatSim1 • Convolve with atmospheric PSF • Transform by geometric distortions and PSF due to optics • Transform by geometric distortions due to CCD glowing edge effect • Cosmic rays

  16. ImSim1 Outputs • Science images, 300 sq deg, 2 tilings in each of griz, ~1 TB • Biases, flat fields • Standard star images

  17. CatSim2/ImSim2 (or beyond) • 5000 sq deg catalog simulation; 1 month of DES imaging data • Improve N-body simulation resolution to get low luminosity galaxies (e.g., MareNostrum Supercomputer simulations via Barcelona) • Improve redshift-luminosity-color-shape-clustering correlations using deeper samples (e.g., RCS/CNOC2, GOODS, ALHAMBRA) • Use ray tracing to improve shear field resolution to enable cosmic shear measurement • Include temporal and spatial correlations of atmospheric PSF, as well as additional contributions from the telescope (e.g., primary mirror de-centering) • Discussion of simulation features and science analysis goals at May 2005 collaboration meeting

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