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DESpec survey strategy : realistic mock catalogue and target selection Stephanie Jouvel, Filipe Abdalla, Huan Lin, James Annis, Richard Kron 22 jun 2011
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PLAN : Investigate DESpec survey strategy Build realistic Mock Catalogues of the DES + VISTA survey Derive spectrograph/fibers sensitivities for ground-based observation Investigate redshift distribution and galaxy density for DESpec science Which tragetting strategy ? What criterion in photoz or color-color space ?
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3 Galaxy Properties from Deep Surveys the VVDS “Deep” survey VIMOS/VLT deep spectroscopic survey on ~0.5 sq.deg ~9000 spectra from 0<z<5 down to I AB ~24 (magnitude selected) the COSMOS survey 2deg 2 (representative) 30 photometric bands from UV to IR with HST, Galex, Spitzer, Subaru, VLA, NOAO HST/ACS I band observation: galaxy sizes & shapes zCosmos spectroscopic survey Le fèvre et al. 2005 Koekemoer et al. 2007
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4 Building Mock Catalogues GOODS Luminosity Function catalogue COSMOS Mock catalogue COSMOS catalogue (position, size, photometry) 1 million galaxies Photoz, SED, emission lines Photometry in DE mission filter sets + Photometric errors DE Forecast Simulated Catalogue based on GOODS LF(z,type) COSMOS size distribution, emission lines Jouvel et al. 2009 Jouvel et al 2010 GOODS LF from Dahlen et al. 2005 COSMOS photoz from Ilbert et al. 2009 Stephanie Jouvel - Realistic redshift distribution, - Realistic size distribution, - Emission line fluxes catalogue Use this catalogue
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5 COSMOS Mock Catalog (CMC) Construction using the properties of the COSMOS-ACS WL catalog using : - realistic photometric redshift distribution 30 photometric bands calibrated with spectroscopic redshift : > zCOSMOS bright (I~22 AB) > zCOSMOS faint (I~25 AB) > MIPS-spectro-z sample - best-fit template from this photoz distribution - galaxy size measured by Sextractor from Leauthaud et al 2007 Validation of the CMC using : - GOODS N&S visible - UDF visible + jh band - VVDS Ks band + spectro-z - GOODS-MUSIC Ks band
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6 COSMOS Mock Catalogue(CMC) Stephanie Jouvel We want precision cosmology Need for realistic mock catalogues to test photoz codes : - Realistic redshift distribution Impacts DE FoM from WL - Realistic distribution of galaxy sizes in redshift and magnitude => Realistic noise distribution impact photoz results -Emission line catalogue Create spectroscopic catalogue to study photoz calibration
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7 COSMOS Mock Catalog (CMC) : Validation Emission line prediction : Kennicutt et al. 1998 : UV-OII relation Validation of the redshift distribution and emission line fluxes using the VVDS-DEEP I~24 AB (Lamareille et al 2008) Jouvel et al. 2009
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8 Spectroscopic Success Rate (SSR) : Validation using VVDS Validation : reproducing the VVDS SSR SSR : galaxy rate for which we will be able to measure a redshift Jouvel et al. 2009
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9 PhotoZ Calibration Survey (PZCS): Spectroscopic Success Rate (SSR) WIDE NIR photometric calibration (BAO–RD survey) template calibration: - DEEP-visible-NIR - DEEP-NIR Jouvel et al. 2009 In the context of the JDEM survey we simulated different spectroscopic surveys :
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10 SSR Forecast for PZCS Forecast : -DEEP-NIR space survey (PZCS) DEEP-NIR : I~27 0.5<z<3.5 35gal/arcmin2 Jouvel et al. 2009
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11 DEEP-vis-NIR : I~27 0<z<3.5 60gal/arcmin2 SSR forecast for PZCS Forecast : DEEP-visible-NIR space survey (PZCS) Jouvel et al. 2009
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12 WIDE-NIR : H ~22 0.5<z<1.5 5gal/arcmin2 SSR Forecast for PZCS Forecast : WIDE-NIR space survey (BAO like) Jouvel et al. 2009
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DESpec survey strategy : 1. Mock catalogue and photoz
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DES+VISTA photometric redshift ANNz training with 10000 galaxies Le Phare with COSMOS templates
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DESpec survey strategy : 2. Target selection
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Line sensitivities from Huan Lin - Sensitivities for 30 mins exposure time on 2 arcsec ø fibers (70% light fraction) - Resolution R=2500 at 0.9um. - Calculation include DES throughput + sky noise and atmospheric lines from Hanuschik (2003)
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Redshift distribution from em lines Redshift distribution of emission line galaxies selected with : - I (DES) < 23 - 1 < photoz < 2 - at least one em line detected at 5 sigma Photoz with Le Phare (template fitting method) u DES+VISTA Can we select the emission line galaxies based on DES+VISTA photometry only ? Total of roughly 12000 gal/deg2
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Multidimensional method based on NN selection
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Use of NN to select em line galaxies We assign a value of : - 1 for targetted em line galaxies - 0 for non targetted galaxies We then use ANNz and train a NN on a sample of 10000 galaxies from the CMC (DES+VISTA) Results for i(DES) < 24
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Which ANNz selection criterion ? Fig : Cumulated nbr galaxies/deg2 fct ANNz target probability We suggest a selection criterion of 0.8 yielding to : -7500 emission line galaxies / deg2 i(DES)<24 - and a contamination of 800 gal/deg2 i(DES)<24 0.8
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Which ANNz selection criterion ? Solid : percentage of galaxies for which we will measure a redshift/total nbr gal & Dashed : SSR fct ANNz target probability We suggest a selection criterion of 0.8 yielding to : -7500 emission line galaxies / deg2 i(DES)<24 - and a contamination of 800 gal/deg2 i(DES)<24
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Redshift distribution of ANNz sel 0.8
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Redshift distribution / em lines gal
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Line sensitivities from Huan Lin 0.6-1um - Sensitivities for 30 mins exposure time on 2 arcsec ø fibers (70% light fraction) - Resolution R=2500 at 0.9um. - Calculation include DES throughput + sky noise and atmospheric lines from Hanuschik (2003)
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Use of NN to select em line galaxies We assign a value of : - 1 for targetted em line galaxies - 0 for non targetted galaxies We then use ANNz and train a NN on a sample of 10000 galaxies from the CMC (DES+VISTA) Results for i(DES) < 24 Using Huan Lin sensitivities cut between 0.6-1um
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Which ANNz selection criterion ? Fig : Cumulated nbr galaxies/deg2 fct ANNz target probability We suggest a selection criterion of 0.8 yielding to : -7500 emission line galaxies / deg2 i(DES)<24 - and a contamination of 800 gal/deg2 i(DES)<24 0.8 Using Huan Lin sensitivities cut between 0.6-1um
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Which ANNz selection criterion ? Solid : percentage of galaxies for which we will measure a redshift/total nbr gal & Dashed : SSR fct ANNz target probability We suggest a selection criterion of 0.8 yielding to : -7500 emission line galaxies / deg2 i(DES)<24 - and a contamination of 800 gal/deg2 i(DES)<24 Using Huan Lin sensitivities cut between 0.6-1um
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Redshift distribution of ANNz sel 0.8 Using Huan Lin sensitivities cut between 0.6-1um
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Photoz for the NN target galaxies
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Can we do color-color cut ? g-r vs r-i r-i vs i-z It looks difficult to select the OII line in a coloc-color cut. We need a higher dimensional kind of cut such as photoz codes can provide
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Conclusion We simulated a DES+VISTA catalogue using the CMC which include emission line fluxes. Huan Lin derived a fiber sensitivities including all instruments troughput and sky noise including astmospheric lines for a DESpec instrument. Using Huan Lin sensitivities we can select emission line galaxies from DES+VISTA photometry using ANNz. We suggest a selection criterion of 0.8 with a yield of 8000gal/deg2 for i(DES)<24 and a success rate of 93% or 5000gal/deg2 i(DES)<23 and a success rate of 95% (to verify). A color-color cut does not seem the optimal solution to select target for DESpec.
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34 COSMOS Mock Catalog (CMC): Validation Jouvel et al. 2009
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35 COSMOS Mock Catalogue(CMC) Stephanie Jouvel We want precision cosmology Need for realistic mock catalogues to test photoz codes : - Realistic redshift distribution Impacts DE FoM from WL - Realistic distribution of galaxy sizes in redshift and magnitude => Realistic noise distribution impact photoz results -Emission line catalogue Create spectroscopic catalogue to study photoz calibration
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Emission lines z = 0 H-a6563 A Ly-a1215 A OII3726-3729 A doublet H-b4861 A OIII4959A and 5007A z~2.5 : Ly-a 4250 OII 13000 z~3.5 : Ly-a 5460
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Results from CMC : Photoz calibration 37 work with Gary Bernstein as part of the SNAP-WL group -Simulation of spectroscopic survey using forecast survey sensitivities for : optical/+NIR surveys, SHALLOW or DEEP. => No photoz calibration possible for z 1.6 galaxies. => Need of visible + NIR spectroscopy to cover the whole redshift range of future photometric surveys. Jouvel et al. 2009 Stephanie Jouvel
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u* +0.019 g’ -0.079 r’ -0.002 i’ 0 Z’ -0.008 Photoz : Need for spectroscopic calibration Successful method to remove systematic trends Importance of the zero-point calibration Further improvement of the templates Ilbert et al.2006
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