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Dark Energy Survey Year 1 Results: redshift distributions of the weak-lensing source galaxies

Hoyle, B. and Eifler, T. F. (2018) Dark Energy Survey Year 1 Results: redshift distributions of the weak-lensing source galaxies. Monthly Notices of the Royal Astronomical Society, 478 (1). pp. 592-610. ISSN 0035-8711.

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We describe the derivation and validation of redshift distribution estimates and their uncertainties for the populations of galaxies used as weak-lensing sources in the Dark Energy Survey (DES) Year 1 cosmological analyses. The Bayesian Photometric Redshift (BPZ) code is used to assign galaxies to four redshift bins between z ≈ 0.2 and ≈1.3, and to produce initial estimates of the lensing-weighted redshift distributions n^i_(PZ)(z)∝dn^i/dz for members of bin i. Accurate determination of cosmological parameters depends critically on knowledge of n^i, but is insensitive to bin assignments or redshift errors for individual galaxies. The cosmological analyses allow for shifts n^i(z)=n^i_(PZ)(z−Δz^i) to correct the mean redshift of n^i(z) for biases in n^i_(PZ). The Δz^i are constrained by comparison of independently estimated 30-band photometric redshifts of galaxies in the Cosmic Evolution Survey (COSMOS) field to BPZ estimates made from the DES griz fluxes, for a sample matched in fluxes, pre-seeing size, and lensing weight to the DES weak-lensing sources. In companion papers, the Δziof the three lowest redshift bins are further constrained by the angular clustering of the source galaxies around red galaxies with secure photometric redshifts at 0.15 < z < 0.9. This paper details the BPZ and COSMOS procedures, and demonstrates that the cosmological inference is insensitive to details of the n^i(z) beyond the choice of Δzi. The clustering and COSMOS validation methods produce consistent estimates of Δz^i in the bins where both can be applied, with combined uncertainties of σΔ_(z^i_ = 0.015,0.013,0.011, and 0.022 in the four bins. Repeating the photo-z procedure instead using the Directional Neighbourhood Fitting algorithm, or using the n^i(z) estimated from the matched sample in COSMOS, yields no discernible difference in cosmological inferences.

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Additional Information:© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2018 March 16. Received 2018 March 12; in original form 2017 August 14. Published: 18 April 2018. Support for DG was provided by NASA through Einstein Postdoctoral Fellowship grant number PF5-160138 awarded by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-03060. Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, the Center for Cosmology and Astro-Particle Physics at the Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnológico and the Ministério da Ciência, Tecnologia e Inovação, the Deutsche Forschungsgemeinschaft, and the Collaborating Institutions in the DES. The Collaborating Institutions are Argonne National Laboratory, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas-Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the University of Edinburgh, the Eidgenössische Technische Hochschule Zürich, Fermi National Accelerator Laboratory, the University of Illinois at Urbana-Champaign, the Institut de Ciències de l’Espai (IEEC/CSIC), the Institut de Física d’Altes Energies, Lawrence Berkeley National Laboratory, the Ludwig-Maximilians Universität München and the associated Excellence Cluster Universe, the University of Michigan, the National Optical Astronomy Observatory, the University of Nottingham, The Ohio State University, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator Laboratory, Stanford University, the University of Sussex, Texas A&M University, and the OzDES Membership Consortium. Based in part on observations at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy under a cooperative agreement with the National Science Foundation. The DES data management system is supported by the National Science Foundation under grant numbers AST-1138766 and AST-1536171. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2015-71825, ESP2015-88861, FPA2015-68048, SEV-2012-0234, SEV-2016-0597, and MDM-2015-0509, some of which include ERDF funds from the European Union. IFAE is partially funded by the CERCA programme of the Generalitat de Catalunya. Research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013) including ERC grant agreements 240672, 291329, and 306478. We acknowledge support from the Australian Research Council Centre of Excellence for All-sky Astrophysics, through project number CE110001020. This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. Based in part on zCOSMOS observations carried out using the Very Large Telescope at the ESO Paranal Observatory under Programme ID: LP175.A-0839.
Funding AgencyGrant Number
NASA Einstein FellowshipPF5-160138
Ministerio de Economía, Industria y Competitividad (MINECO)AYA2015-71825
Ministerio de Economía, Industria y Competitividad (MINECO)ESP2015-88861
Ministerio de Economía, Industria y Competitividad (MINECO)FPA2015-68048
Centro de Excelencia Severo OchoaSEV-2012-0234
Centro de Excelencia Severo OchoaSEV-2016-0597
Ministerio de Economía, Industria y Competitividad (MINECO)MDM-2015-0509
European Regional Development Fund, EstoniaUNSPECIFIED
Generalitat de CatalunyaUNSPECIFIED
European Research Council (ERC)240672
European Research Council (ERC)291329
European Research Council (ERC)306478
Australian Research CouncilCE110001020
Department of Energy (DOE)DE-AC02-07CH11359
Subject Keywords:methods: data analysis – catalogues – surveys
Record Number:CaltechAUTHORS:20180809-094603640
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Official Citation:B Hoyle, D Gruen, G M Bernstein, M M Rau, J De Vicente, W G Hartley, E Gaztanaga, J DeRose, M A Troxel, C Davis, A Alarcon, N MacCrann, J Prat, C Sánchez, E Sheldon, R H Wechsler, J Asorey, M R Becker, C Bonnett, A Carnero Rosell, D Carollo, M Carrasco Kind, F J Castander, R Cawthon, C Chang, M Childress, T M Davis, A Drlica-Wagner, M Gatti, K Glazebrook, J Gschwend, S R Hinton, J K Hoormann, A G Kim, A King, K Kuehn, G Lewis, C Lidman, H Lin, E Macaulay, M A G Maia, P Martini, D Mudd, A Möller, R C Nichol, R L C Ogando, R P Rollins, A Roodman, A J Ross, E Rozo, E S Rykoff, S Samuroff, I Sevilla-Noarbe, R Sharp, N E Sommer, B E Tucker, S A Uddin, T N Varga, P Vielzeuf, F Yuan, B Zhang, T M C Abbott, F B Abdalla, S Allam, J Annis, K Bechtol, A Benoit-Lévy, E Bertin, D Brooks, E Buckley-Geer, D L Burke, M T Busha, D Capozzi, J Carretero, M Crocce, C B D’Andrea, L N da Costa, D L DePoy, S Desai, H T Diehl, P Doel, T F Eifler, J Estrada, A E Evrard, E Fernandez, B Flaugher, P Fosalba, J Frieman, J García-Bellido, D W Gerdes, T Giannantonio, D A Goldstein, R A Gruendl, G Gutierrez, K Honscheid, D J James, M Jarvis, T Jeltema, M W G Johnson, M D Johnson, D Kirk, E Krause, S Kuhlmann, N Kuropatkin, O Lahav, T S Li, M Lima, M March, J L Marshall, P Melchior, F Menanteau, R Miquel, B Nord, C R O’Neill, A A Plazas, A K Romer, M Sako, E Sanchez, B Santiago, V Scarpine, R Schindler, M Schubnell, M Smith, R C Smith, M Soares-Santos, F Sobreira, E Suchyta, M E C Swanson, G Tarle, D Thomas, D L Tucker, V Vikram, A R Walker, J Weller, W Wester, R C Wolf, B Yanny, J Zuntz, DES Collaboration; Dark Energy Survey Year 1 Results: redshift distributions of the weak-lensing source galaxies, Monthly Notices of the Royal Astronomical Society, Volume 478, Issue 1, 21 July 2018, Pages 592–610,
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ID Code:88685
Deposited By: Tony Diaz
Deposited On:09 Aug 2018 17:01
Last Modified:09 Aug 2018 17:01

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