The STRong lensing Insights into the dark energy survey (STRIDES) 2017/2018 follow-up campaign: Discovery of 10 lensed quasars and 10 quasar pairs

C. Lemon; M. W. Auger; McMahon R. McMahon; T. Anguita; Y. Apostolovski; G. C.F. Chen; C. D. Fassnacht; A. D. Melo; V. Motta; A. Shajib; T. Treu; A. Agnello; E. Buckley-Geer; P. L. Schechter; S. Birrer; T. Collett; F. Courbin; C. E. Rusu; T. M.C. Abbott; S. Allam; J. Annis; S. Avila; E. Bertin; D. Brooks; D. L. Burke; A. Carnero Rosell; M. Carrasco Kind; J. Carretero; M. Costanzi; L. N. Da Costa; J. De Vicente; S. Desai; T. F. Eifler; B. Flaugher; J. Frieman; J. García-Bellido; E. Gaztanaga; D. W. Gerdes; D. Gruen; R. A. Gruendl; J. Gschwend; G. Gutierrez; K. Honscheid; D. J. James; A. Kim; E. Krause; K. Kuehn; N. Kuropatkin; O. Lahav; M. Lima; H. Lin; M. A.G. Maia; M. March; J. L. Marshall; F. Menanteau; R. Miquel; A. Palmese; F. Paz-Chinchon; A. A. Plazas; A. Roodman; E. Sanchez; M. Schubnell; S. Serrano; M. Smith; M. Soares-Santos; E. Suchyta; G. Tarle; A. R. Walker

doi:10.1093/MNRAS/STAA652

The STRong lensing Insights into the dark energy survey (STRIDES) 2017/2018 follow-up campaign: Discovery of 10 lensed quasars and 10 quasar pairs

C. Lemon, M. W. Auger, McMahon R. McMahon, T. Anguita, Y. Apostolovski, G. C.F. Chen, C. D. Fassnacht, A. D. Melo, V. Motta, A. Shajib, T. Treu, A. Agnello, E. Buckley-Geer, P. L. Schechter, S. Birrer, T. Collett, F. Courbin, C. E. Rusu, T. M.C. Abbott, S. AllamJ. Annis, S. Avila, E. Bertin, D. Brooks, D. L. Burke, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, M. Costanzi, L. N. Da Costa, J. De Vicente, S. Desai, T. F. Eifler, B. Flaugher, J. Frieman, J. García-Bellido, E. Gaztanaga, D. W. Gerdes, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, K. Honscheid, D. J. James, A. Kim, E. Krause, K. Kuehn, N. Kuropatkin, O. Lahav, M. Lima, H. Lin, M. A.G. Maia, M. March, J. L. Marshall, F. Menanteau, R. Miquel, A. Palmese, F. Paz-Chinchon, A. A. Plazas, A. Roodman, E. Sanchez, M. Schubnell, S. Serrano, M. Smith, M. Soares-Santos, E. Suchyta, G. Tarle, A. R. Walker

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Abstract

We report the results of the STRong lensing Insights into the Dark Energy Survey (STRIDES) follow-up campaign of the late 2017/early 2018 season. We obtained spectra of 65 lensed quasar candidates with ESO Faint Object Spectrograph and Camera 2 on the NTT and Echellette Spectrograph and Imager onKeck, confirming 10 newlensed quasars and 10 quasar pairs. Eight lensed quasars are doubly imaged with source redshifts between 0.99 and 2.90, one is triply imaged (DESJ0345.2545, z = 1.68), and one is quadruply imaged (quad: DESJ0053.2012, z = 3.8). Singular isothermal ellipsoid models for the doubles, based on high-resolution imaging from SAMI on Southern Astrophysical Research Telescope or Near InfraRed Camera 2 on Keck, give total magnifications between 3.2 and 5.6, and Einstein radii between 0.49 and 1.97 arcsec. After spectroscopic follow-up, we extract multi-epoch grizY photometry of confirmed lensed quasars and contaminant quasar+star pairs from DES data using parametric multiband modelling, and compare variability in each system's components. By measuring the reduced χ2 associated with fitting all epochs to the samemagnitude, we find a simple cut on the less variable component that retains all confirmed lensed quasars, while removing 94 per cent of contaminant systems. Based on our spectroscopic follow-up, this variability information improves selection of lensed quasars and quasar pairs from 34-45 per cent to 51-70 per cent, with most remaining contaminants being star-forming galaxies. Using mock lensed quasar light curves we demonstrate that selection based only on variability will over-represent the quad fraction by 10 per cent over a complete DES magnitude-limited sample, explained by the magnification bias and hence lower luminosity/more variable sources in quads.

Original language	English
Pages (from-to)	3491-3511
Number of pages	21
Journal	Monthly Notices of the Royal Astronomical Society
Volume	494
Issue number	3
DOIs	https://doi.org/10.1093/MNRAS/STAA652
State	Published - 2020

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\u00B8\u00E3o Carlos Chagas Filho de Amparo \u00E0 Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Cient\u00EDfico e Tecnol\u00F3gico and the Minist\u00E9rio da Ci\u00EAncia, Tecnologia e Inovac\u00B8\u00E3o, the Deutsche Forschungsgemeinschaft, and the Collaborating Institutions in the Dark Energy Survey. This work is supported by the Swiss National Science Foundation (SNSF). This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (COSMICLENS: grant agreement no. 787886). AA was supported by a grant from Villum Fonden (project number 16599). This project is partially funded by the Danish council for independent research under the project 'Fundamentals of Dark Matter Structures', DFF - 6108-00470. TA acknowledges support from Proyecto FONDECYT No. 1190335. AJS acknowledges support from the National Aeronautics and Space Administration through the Space Telescope Science Institute grant HST-GO-15320 and from University of California, Los Angeles graduate division through a dissertation year fellowship. CDF and GCFC acknowledge support for this work from the National Science Foundation under grant no. AST-1715611. TT acknowledges support by NSF through grants AST-1450141 and AST-1906976 and by the Packard Foundation through a Packard Fellowship. ADM acknowledges grant support from project CONICYTPFCHA/Doctorado Nacional 2017 folio 21171499. This work is supported by the Swiss National Science Foundation (SNSF). This project has received funding from the European Research Council (ERC) under the European Union\u2019s Horizon 2020 research and innovation program (COSMICLENS: grant agreement no. 787886). AA was supported by a grant from Villum Fonden (project number 16599). This project is partially funded by the Danish council for independent research under the project \u2018Fundamentals of Dark Matter Structures\u2019, DFF \u2013 6108-00470. TA acknowledges support from Proyecto FONDECYT No. 1190335. AJS acknowledges support from the National Aeronautics and Space Administration through the Space Telescope Science Institute grant HST-GO-15320 and from University of California, Los Angeles graduate division through a dissertation year fellowship. CDF and GCFC acknowledge support for this work from the National Science Foundation under grant no. AST-1715611. TT acknowledges support by NSF through grants AST-1450141 and AST-1906976 and by the Packard Foundation through a Packard Fellowship. ADM acknowledges grant support from project CONICYT-PFCHA/Doctorado Nacional 2017 folio 21171499. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, ht tps://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Min-ist\u00E9rio da Ci\u00EAncia, Tecnologia, Inovac\u00B8\u00F5es e Comunicac\u00B8\u00F5es (MC-TIC) do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU). VM acknowledges the support of the Centro de Astrof\u00EDsica de Valpara\u00EDso. This study is 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 (AURA) under a cooperative agreement with the National Science Foundation.

Keywords

Gravitational lensing: strong
Methods: observational
Quasars: general

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10.1093/MNRAS/STAA652

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Lemon, C., Auger, M. W., R. McMahon, M., Anguita, T., Apostolovski, Y., Chen, G. C. F., Fassnacht, C. D., Melo, A. D., Motta, V., Shajib, A., Treu, T., Agnello, A., Buckley-Geer, E., Schechter, P. L., Birrer, S., Collett, T., Courbin, F., Rusu, C. E., Abbott, T. M. C., ... Walker, A. R. (2020). The STRong lensing Insights into the dark energy survey (STRIDES) 2017/2018 follow-up campaign: Discovery of 10 lensed quasars and 10 quasar pairs. Monthly Notices of the Royal Astronomical Society, 494(3), 3491-3511. https://doi.org/10.1093/MNRAS/STAA652

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title = "The STRong lensing Insights into the dark energy survey (STRIDES) 2017/2018 follow-up campaign: Discovery of 10 lensed quasars and 10 quasar pairs",

abstract = "We report the results of the STRong lensing Insights into the Dark Energy Survey (STRIDES) follow-up campaign of the late 2017/early 2018 season. We obtained spectra of 65 lensed quasar candidates with ESO Faint Object Spectrograph and Camera 2 on the NTT and Echellette Spectrograph and Imager onKeck, confirming 10 newlensed quasars and 10 quasar pairs. Eight lensed quasars are doubly imaged with source redshifts between 0.99 and 2.90, one is triply imaged (DESJ0345.2545, z = 1.68), and one is quadruply imaged (quad: DESJ0053.2012, z = 3.8). Singular isothermal ellipsoid models for the doubles, based on high-resolution imaging from SAMI on Southern Astrophysical Research Telescope or Near InfraRed Camera 2 on Keck, give total magnifications between 3.2 and 5.6, and Einstein radii between 0.49 and 1.97 arcsec. After spectroscopic follow-up, we extract multi-epoch grizY photometry of confirmed lensed quasars and contaminant quasar+star pairs from DES data using parametric multiband modelling, and compare variability in each system's components. By measuring the reduced χ2 associated with fitting all epochs to the samemagnitude, we find a simple cut on the less variable component that retains all confirmed lensed quasars, while removing 94 per cent of contaminant systems. Based on our spectroscopic follow-up, this variability information improves selection of lensed quasars and quasar pairs from 34-45 per cent to 51-70 per cent, with most remaining contaminants being star-forming galaxies. Using mock lensed quasar light curves we demonstrate that selection based only on variability will over-represent the quad fraction by 10 per cent over a complete DES magnitude-limited sample, explained by the magnification bias and hence lower luminosity/more variable sources in quads.",

keywords = "Gravitational lensing: strong, Methods: observational, Quasars: general",

author = "C. Lemon and Auger, {M. W.} and {R. McMahon}, McMahon and T. Anguita and Y. Apostolovski and Chen, {G. C.F.} and Fassnacht, {C. D.} and Melo, {A. D.} and V. Motta and A. Shajib and T. Treu and A. Agnello and E. Buckley-Geer and Schechter, {P. L.} and S. Birrer and T. Collett and F. Courbin and Rusu, {C. E.} and Abbott, {T. M.C.} and S. Allam and J. Annis and S. Avila and E. Bertin and D. Brooks and Burke, {D. L.} and {Carnero Rosell}, A. and {Carrasco Kind}, M. and J. Carretero and M. Costanzi and {Da Costa}, {L. N.} and {De Vicente}, J. and S. Desai and Eifler, {T. F.} and B. Flaugher and J. Frieman and J. Garc{\'i}a-Bellido and E. Gaztanaga and Gerdes, {D. W.} and D. Gruen and Gruendl, {R. A.} and J. Gschwend and G. Gutierrez and K. Honscheid and James, {D. J.} and A. Kim and E. Krause and K. Kuehn and N. Kuropatkin and O. Lahav and M. Lima and H. Lin and Maia, {M. A.G.} and M. March and Marshall, {J. L.} and F. Menanteau and R. Miquel and A. Palmese and F. Paz-Chinchon and Plazas, {A. A.} and A. Roodman and E. Sanchez and M. Schubnell and S. Serrano and M. Smith and M. Soares-Santos and E. Suchyta and G. Tarle and Walker, {A. R.}",

note = "Publisher Copyright: {\textcopyright} 2020 The Author(s).",

year = "2020",

doi = "10.1093/MNRAS/STAA652",

language = "English",

volume = "494",

pages = "3491--3511",

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

issn = "0035-8711",

publisher = "Oxford University Press",

number = "3",

}

Lemon, C, Auger, MW, R. McMahon, M, Anguita, T, Apostolovski, Y, Chen, GCF, Fassnacht, CD, Melo, AD, Motta, V, Shajib, A, Treu, T, Agnello, A, Buckley-Geer, E, Schechter, PL, Birrer, S, Collett, T, Courbin, F, Rusu, CE, Abbott, TMC, Allam, S, Annis, J, Avila, S, Bertin, E, Brooks, D, Burke, DL, Carnero Rosell, A, Carrasco Kind, M, Carretero, J, Costanzi, M, Da Costa, LN, De Vicente, J, Desai, S, Eifler, TF, Flaugher, B, Frieman, J, García-Bellido, J, Gaztanaga, E, Gerdes, DW, Gruen, D, Gruendl, RA, Gschwend, J, Gutierrez, G, Honscheid, K, James, DJ, Kim, A, Krause, E, Kuehn, K, Kuropatkin, N, Lahav, O, Lima, M, Lin, H, Maia, MAG, March, M, Marshall, JL, Menanteau, F, Miquel, R, Palmese, A, Paz-Chinchon, F, Plazas, AA, Roodman, A, Sanchez, E, Schubnell, M, Serrano, S, Smith, M, Soares-Santos, M, Suchyta, E, Tarle, G & Walker, AR 2020, 'The STRong lensing Insights into the dark energy survey (STRIDES) 2017/2018 follow-up campaign: Discovery of 10 lensed quasars and 10 quasar pairs', Monthly Notices of the Royal Astronomical Society, vol. 494, no. 3, pp. 3491-3511. https://doi.org/10.1093/MNRAS/STAA652

TY - JOUR

T1 - The STRong lensing Insights into the dark energy survey (STRIDES) 2017/2018 follow-up campaign

T2 - Discovery of 10 lensed quasars and 10 quasar pairs

AU - Lemon, C.

AU - Auger, M. W.

AU - R. McMahon, McMahon

AU - Anguita, T.

AU - Apostolovski, Y.

AU - Chen, G. C.F.

AU - Fassnacht, C. D.

AU - Melo, A. D.

AU - Motta, V.

AU - Shajib, A.

AU - Treu, T.

AU - Agnello, A.

AU - Buckley-Geer, E.

AU - Schechter, P. L.

AU - Birrer, S.

AU - Collett, T.

AU - Courbin, F.

AU - Rusu, C. E.

AU - Abbott, T. M.C.

AU - Allam, S.

AU - Annis, J.

AU - Avila, S.

AU - Bertin, E.

AU - Brooks, D.

AU - Burke, D. L.

AU - Carnero Rosell, A.

AU - Carrasco Kind, M.

AU - Carretero, J.

AU - Costanzi, M.

AU - Da Costa, L. N.

AU - De Vicente, J.

AU - Desai, S.

AU - Eifler, T. F.

AU - Flaugher, B.

AU - Frieman, J.

AU - García-Bellido, J.

AU - Gaztanaga, E.

AU - Gerdes, D. W.

AU - Gruen, D.

AU - Gruendl, R. A.

AU - Gschwend, J.

AU - Gutierrez, G.

AU - Honscheid, K.

AU - James, D. J.

AU - Kim, A.

AU - Krause, E.

AU - Kuehn, K.

AU - Kuropatkin, N.

AU - Lahav, O.

AU - Lima, M.

AU - Lin, H.

AU - Maia, M. A.G.

AU - March, M.

AU - Marshall, J. L.

AU - Menanteau, F.

AU - Miquel, R.

AU - Palmese, A.

AU - Paz-Chinchon, F.

AU - Plazas, A. A.

AU - Roodman, A.

AU - Sanchez, E.

AU - Schubnell, M.

AU - Serrano, S.

AU - Smith, M.

AU - Soares-Santos, M.

AU - Suchyta, E.

AU - Tarle, G.

AU - Walker, A. R.

PY - 2020

Y1 - 2020

N2 - We report the results of the STRong lensing Insights into the Dark Energy Survey (STRIDES) follow-up campaign of the late 2017/early 2018 season. We obtained spectra of 65 lensed quasar candidates with ESO Faint Object Spectrograph and Camera 2 on the NTT and Echellette Spectrograph and Imager onKeck, confirming 10 newlensed quasars and 10 quasar pairs. Eight lensed quasars are doubly imaged with source redshifts between 0.99 and 2.90, one is triply imaged (DESJ0345.2545, z = 1.68), and one is quadruply imaged (quad: DESJ0053.2012, z = 3.8). Singular isothermal ellipsoid models for the doubles, based on high-resolution imaging from SAMI on Southern Astrophysical Research Telescope or Near InfraRed Camera 2 on Keck, give total magnifications between 3.2 and 5.6, and Einstein radii between 0.49 and 1.97 arcsec. After spectroscopic follow-up, we extract multi-epoch grizY photometry of confirmed lensed quasars and contaminant quasar+star pairs from DES data using parametric multiband modelling, and compare variability in each system's components. By measuring the reduced χ2 associated with fitting all epochs to the samemagnitude, we find a simple cut on the less variable component that retains all confirmed lensed quasars, while removing 94 per cent of contaminant systems. Based on our spectroscopic follow-up, this variability information improves selection of lensed quasars and quasar pairs from 34-45 per cent to 51-70 per cent, with most remaining contaminants being star-forming galaxies. Using mock lensed quasar light curves we demonstrate that selection based only on variability will over-represent the quad fraction by 10 per cent over a complete DES magnitude-limited sample, explained by the magnification bias and hence lower luminosity/more variable sources in quads.

AB - We report the results of the STRong lensing Insights into the Dark Energy Survey (STRIDES) follow-up campaign of the late 2017/early 2018 season. We obtained spectra of 65 lensed quasar candidates with ESO Faint Object Spectrograph and Camera 2 on the NTT and Echellette Spectrograph and Imager onKeck, confirming 10 newlensed quasars and 10 quasar pairs. Eight lensed quasars are doubly imaged with source redshifts between 0.99 and 2.90, one is triply imaged (DESJ0345.2545, z = 1.68), and one is quadruply imaged (quad: DESJ0053.2012, z = 3.8). Singular isothermal ellipsoid models for the doubles, based on high-resolution imaging from SAMI on Southern Astrophysical Research Telescope or Near InfraRed Camera 2 on Keck, give total magnifications between 3.2 and 5.6, and Einstein radii between 0.49 and 1.97 arcsec. After spectroscopic follow-up, we extract multi-epoch grizY photometry of confirmed lensed quasars and contaminant quasar+star pairs from DES data using parametric multiband modelling, and compare variability in each system's components. By measuring the reduced χ2 associated with fitting all epochs to the samemagnitude, we find a simple cut on the less variable component that retains all confirmed lensed quasars, while removing 94 per cent of contaminant systems. Based on our spectroscopic follow-up, this variability information improves selection of lensed quasars and quasar pairs from 34-45 per cent to 51-70 per cent, with most remaining contaminants being star-forming galaxies. Using mock lensed quasar light curves we demonstrate that selection based only on variability will over-represent the quad fraction by 10 per cent over a complete DES magnitude-limited sample, explained by the magnification bias and hence lower luminosity/more variable sources in quads.

KW - Gravitational lensing: strong

KW - Methods: observational

KW - Quasars: general

UR - http://www.scopus.com/inward/record.url?scp=85089960899&partnerID=8YFLogxK

U2 - 10.1093/MNRAS/STAA652

DO - 10.1093/MNRAS/STAA652

M3 - Article

AN - SCOPUS:85089960899

SN - 0035-8711

VL - 494

SP - 3491

EP - 3511

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 3

ER -

The STRong lensing Insights into the dark energy survey (STRIDES) 2017/2018 follow-up campaign: Discovery of 10 lensed quasars and 10 quasar pairs

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