Dark energy survey year 1 results: Redshift distributions of the weak-lensing source galaxies

DES Collaboration

doi:10.1093/mnras/sty957

Dark energy survey year 1 results: Redshift distributions of the weak-lensing source galaxies

DES Collaboration

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Abstract

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_PZ ⁱ(z) ∝ dnⁱ/dz for members of bin i. Accurate determination of cosmological parameters depends critically on knowledge of ni, but is insensitive to bin assignments or redshift errors for individual galaxies. The cosmological analyses allow for shifts nⁱ (z) = n_PZ ⁱ(z - Δzⁱ) to correct themean redshift of nⁱ(z) for biases in n_PZ ⁱ. The Δzⁱ 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 Δzⁱ of 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 nⁱ(z) beyond the choice of Δzⁱ. The clustering and COSMOS validation methods produce consistent estimates of Δzⁱ in the bins where both can be applied, with combined uncertainties of σΔzⁱ = 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 nⁱ(z) estimated from the matched sample in COSMOS, yields no discernible difference in cosmological inferences.

Original language	English
Pages (from-to)	592-610
Number of pages	19
Journal	Monthly Notices of the Royal Astronomical Society
Volume	478
Issue number	1
DOIs	https://doi.org/10.1093/mnras/sty957
State	Published - Jul 21 2018

Bibliographical note

Publisher Copyright:
© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.

Funding

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, Fundac¸ão Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desen-volvimento Científico e Tecnológico and the Ministério da Ciência, Tecnologia e Inovac¸ão, the Deutsche Forschungsgemeinschaft, and the Collaborating Institutions in the DES. 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. 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 Frame-work 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. 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. 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, theMinistry of Science and Education of Spain, the Science and Technology FacilitiesCouncil of theUnitedKingdom, theHigher 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, Funda??o Carlos Chagas Filho de Amparo? Pesquisa do Estado do Rio de Janeiro, Conselho Nacional deDesenvolvimento Cient?fico e Tecnol?gico and the Minist?rio da Ci?ncia, Tecnologia e Inova??o, 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 Energ?ticas, Medioambientales y Tecnol?gicas-Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the University of Edinburgh, the Eidgen?ssische Technische Hochschule Z?rich, Fermi National Accelerator Laboratory, the University of Illinois at Urbana-Champaign, the Institut de Ci?ncies de l'Espai (IEEC/CSIC), the Institut de F?sica d'Altes Energies, Lawrence Berkeley National Laboratory, the Ludwig-Maximilians Universit ?t M?nchen 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, TexasA&MUniversity, and theOzDES 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. TheUnited StatesGovernment 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. 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.

Funders	Funder number
Australian Research Council Centre of Excellence for All-sky Astrophysics	CE110001020
Collaborating Institutions in the DES
Conselho Nacional de Desen-volvimento Científico e Tecnológico
Conselho Nacional deDesenvolvimento Cient?fico e Tecnol?gico
DES
DES-Brazil
Eidgen?ssische Technische Hochschule Z?rich
European Union’s Seventh Frame-work Programme
FP7/2007
Fermi Research Alliance, LLC	DE-AC02-07CH11359
Institut de Ci?ncies de l'Espai
Institut de F?sica d'Altes Energies
Kavli Institute of Cosmological Physics at the University of Chicago
Ludwig-Maximilians Universit ?
Minist?rio da Ci?ncia, Tecnologia e Inova
Ministry of Science and Education of Spain
Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University
National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign
Office of High Energy Physics
Science and Technology FacilitiesCouncil of theUnitedKingdom
U.S. National Science Foundation
United States Government
National Science Foundation	681431, 1138766, AST-1138766, 240672, 306478, 291329, AST-1536171
U.S. Department of Energy
National Aeronautics and Space Administration	PF5-160138, NAS8-03060
University of Illinois at Urbana-Champaign
Stanford University
Kavli Institute for Theoretical Physics, University of California, Santa Barbara
Office of Science
High Energy Physics
Argonne National Laboratory
Lawrence Berkeley National Laboratory
Center for Advanced Study, University of Illinois at Urbana-Champaign
University of California, Santa Cruz
University of Pennsylvania
Ohio State University
University of Chicago
University of Michigan
Association of Canadian Universities for Research in Astronomy
University of Portsmouth
Smithsonian Astrophysical Observatory
Higher Education Funding Council for England
Center for Cosmology and Astroparticle Physics, Ohio State University
Science and Technology Facilities Council
University of Cambridge
University College London
European Commission
European Research Council
University of Nottingham
University of Sussex
University of Edinburgh
European Geosciences Union
Deutsche Forschungsgemeinschaft
Generalitat de Catalunya
Ministerio de Economía y Competitividad	ESP2015-88861, SEV-2016-0597, MDM-2015-0509, FPA2015-68048, SEV-2012-0234, AYA2015-71825
Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro
European Southern Observatory	LP175.A-0839
Financiadora de Estudos e Projetos
Seventh Framework Programme
Ministério da Ciência e Tecnologia
European Regional Development Fund
Centre of Excellence for Electromaterials Science, Australian Research Council
National Science Foundation
of Science and Education of Spain

Keywords

Catalogues
Methods: Data analysis
Surveys

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10.1093/mnras/sty957

Cite this

@article{dc1aea4b5aa04906b5db560862b5a0f9,

title = "Dark energy survey year 1 results: Redshift distributions of the weak-lensing source galaxies",

abstract = "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 nPZ i(z) ∝ dni/dz for members of bin i. Accurate determination of cosmological parameters depends critically on knowledge of ni, but is insensitive to bin assignments or redshift errors for individual galaxies. The cosmological analyses allow for shifts ni (z) = nPZ i(z - Δzi) to correct themean redshift of ni(z) for biases in nPZ i. The Δzi 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 Δzi of 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 ni(z) beyond the choice of Δzi. The clustering and COSMOS validation methods produce consistent estimates of Δzi in the bins where both can be applied, with combined uncertainties of σΔzi = 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 ni(z) estimated from the matched sample in COSMOS, yields no discernible difference in cosmological inferences.",

keywords = "Catalogues, Methods: Data analysis, Surveys",

author = "{DES Collaboration} and B. Hoyle and D. Gruen and Bernstein, {G. M.} and Rau, {M. M.} and {De Vicente}, J. and Hartley, {W. G.} and E. Gaztanaga and J. DeRose and Troxel, {M. A.} and C. Davis and A. Alarcon and N. MacCrann and J. Prat and C. S{\'a}nchez and E. Sheldon and Wechsler, {R. H.} and J. Asorey and Becker, {M. R.} and C. Bonnett and Rosell, {A. Carnero} and D. Carollo and Kind, {M. Carrasco} and Castander, {F. J.} and R. Cawthon and C. Chang and M. Childress and Davis, {T. M.} and A. Drlica-Wagner and M. Gatti and K. Glazebrook and J. Gschwend and Hinton, {S. R.} and Hoormann, {J. K.} and Kim, {A. G.} and A. King and K. Kuehn and G. Lewis and C. Lidman and H. Lin and E. Macaulay and Maia, {M. A.G.} and P. Martini and D. Mudd and A. M{\"o}ller and Nichol, {R. C.} and Ogando, {R. L.C.} and Rollins, {R. P.} and A. Roodman and Ross, {A. J.} and E. Suchyta",

note = "Publisher Copyright: {\textcopyright} 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.",

year = "2018",

month = jul,

day = "21",

doi = "10.1093/mnras/sty957",

language = "English",

volume = "478",

pages = "592--610",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "Oxford University Press",

number = "1",

}

TY - JOUR

T1 - Dark energy survey year 1 results

T2 - Redshift distributions of the weak-lensing source galaxies

AU - DES Collaboration

AU - Hoyle, B.

AU - Gruen, D.

AU - Bernstein, G. M.

AU - Rau, M. M.

AU - De Vicente, J.

AU - Hartley, W. G.

AU - Gaztanaga, E.

AU - DeRose, J.

AU - Troxel, M. A.

AU - Davis, C.

AU - Alarcon, A.

AU - MacCrann, N.

AU - Prat, J.

AU - Sánchez, C.

AU - Sheldon, E.

AU - Wechsler, R. H.

AU - Asorey, J.

AU - Becker, M. R.

AU - Bonnett, C.

AU - Rosell, A. Carnero

AU - Carollo, D.

AU - Kind, M. Carrasco

AU - Castander, F. J.

AU - Cawthon, R.

AU - Chang, C.

AU - Childress, M.

AU - Davis, T. M.

AU - Drlica-Wagner, A.

AU - Gatti, M.

AU - Glazebrook, K.

AU - Gschwend, J.

AU - Hinton, S. R.

AU - Hoormann, J. K.

AU - Kim, A. G.

AU - King, A.

AU - Kuehn, K.

AU - Lewis, G.

AU - Lidman, C.

AU - Lin, H.

AU - Macaulay, E.

AU - Maia, M. A.G.

AU - Martini, P.

AU - Mudd, D.

AU - Möller, A.

AU - Nichol, R. C.

AU - Ogando, R. L.C.

AU - Rollins, R. P.

AU - Roodman, A.

AU - Ross, A. J.

AU - Suchyta, E.

PY - 2018/7/21

Y1 - 2018/7/21

N2 - 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 nPZ i(z) ∝ dni/dz for members of bin i. Accurate determination of cosmological parameters depends critically on knowledge of ni, but is insensitive to bin assignments or redshift errors for individual galaxies. The cosmological analyses allow for shifts ni (z) = nPZ i(z - Δzi) to correct themean redshift of ni(z) for biases in nPZ i. The Δzi 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 Δzi of 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 ni(z) beyond the choice of Δzi. The clustering and COSMOS validation methods produce consistent estimates of Δzi in the bins where both can be applied, with combined uncertainties of σΔzi = 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 ni(z) estimated from the matched sample in COSMOS, yields no discernible difference in cosmological inferences.

AB - 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 nPZ i(z) ∝ dni/dz for members of bin i. Accurate determination of cosmological parameters depends critically on knowledge of ni, but is insensitive to bin assignments or redshift errors for individual galaxies. The cosmological analyses allow for shifts ni (z) = nPZ i(z - Δzi) to correct themean redshift of ni(z) for biases in nPZ i. The Δzi 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 Δzi of 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 ni(z) beyond the choice of Δzi. The clustering and COSMOS validation methods produce consistent estimates of Δzi in the bins where both can be applied, with combined uncertainties of σΔzi = 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 ni(z) estimated from the matched sample in COSMOS, yields no discernible difference in cosmological inferences.

KW - Catalogues

KW - Methods: Data analysis

KW - Surveys

UR - http://www.scopus.com/inward/record.url?scp=85048497275&partnerID=8YFLogxK

U2 - 10.1093/mnras/sty957

DO - 10.1093/mnras/sty957

M3 - Article

AN - SCOPUS:85048497275

SN - 0035-8711

VL - 478

SP - 592

EP - 610

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 1

ER -

Dark energy survey year 1 results: Redshift distributions of the weak-lensing source galaxies

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