VDES J2325-5229 a z = 2.7 gravitationally lensed quasar discovered using morphology-independent supervised machine learning

Fernanda Ostrovski; Richard G. McMahon; Andrew J. Connolly; Cameron A. Lemon; Matthew W. Auger; Manda Banerji; Johnathan M. Hung; Sergey E. Koposov; Christopher E. Lidman; Sophie L. Reed; Sahar Allam; Aurélien Benoit-Lévy; Emmanuel Bertin; David Brooks; Elizabeth Buckley-Geer; Aurelio Carnero Rosell; Matias Carrasco Kind; Jorge Carretero; Carlos E. Cunha; Luiz N. da Costa; Shantanu Desai; H. Thomas Diehl; Jörg P. Dietrich; August E. Evrard; David A. Finley; Brenna Flaugher; Pablo Fosalba; Josh Frieman; David W. Gerdes; Daniel A. Goldstein; Daniel Gruen; Robert A. Gruendl; Gaston Gutierrez; Klaus Honscheid; David J. James; Kyler Kuehn; Nikolay Kuropatkin; Marcos Lima; Huan Lin; Marcio A.G. Maia; Jennifer L. Marshall; Paul Martini; Peter Melchior; Ramon Miquel; Ricardo Ogando; Andrés Plazas Malagón; Kevin Reil; Kathy Romer; Eusebio Sanchez; Basilio Santiago; Vic Scarpine; Ignacio Sevilla-Noarbe; Marcelle Soares-Santos; Flavia Sobreira; Eric Suchyta; Gregory Tarle; Daniel Thomas; Douglas L. Tucker; Alistair R. Walker

doi:10.1093/mnras/stw2958

VDES J2325-5229 a z = 2.7 gravitationally lensed quasar discovered using morphology-independent supervised machine learning

Fernanda Ostrovski, Richard G. McMahon, Andrew J. Connolly, Cameron A. Lemon, Matthew W. Auger, Manda Banerji, Johnathan M. Hung, Sergey E. Koposov, Christopher E. Lidman, Sophie L. Reed, Sahar Allam, Aurélien Benoit-Lévy, Emmanuel Bertin, David Brooks, Elizabeth Buckley-Geer, Aurelio Carnero Rosell, Matias Carrasco Kind, Jorge Carretero, Carlos E. Cunha, Luiz N. da CostaShantanu Desai, H. Thomas Diehl, Jörg P. Dietrich, August E. Evrard, David A. Finley, Brenna Flaugher, Pablo Fosalba, Josh Frieman, David W. Gerdes, Daniel A. Goldstein, Daniel Gruen, Robert A. Gruendl, Gaston Gutierrez, Klaus Honscheid, David J. James, Kyler Kuehn, Nikolay Kuropatkin, Marcos Lima, Huan Lin, Marcio A.G. Maia, Jennifer L. Marshall, Paul Martini, Peter Melchior, Ramon Miquel, Ricardo Ogando, Andrés Plazas Malagón, Kevin Reil, Kathy Romer, Eusebio Sanchez, Basilio Santiago, Vic Scarpine, Ignacio Sevilla-Noarbe, Marcelle Soares-Santos, Flavia Sobreira, Eric Suchyta, Gregory Tarle, Daniel Thomas, Douglas L. Tucker, Alistair R. Walker

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Abstract

We present the discovery and preliminary characterization of a gravitationally lensed quasar with a source redshift z_s = 2.74 and image separation of 2.9 arcsec lensed by a foreground z_l = 0.40 elliptical galaxy. Since optical observations of gravitationally lensed quasars showthe lens system as a superposition of multiple point sources and a foreground lensing galaxy, we have developed a morphology-independent multi-wavelength approach to the photometric selection of lensed quasar candidates based on Gaussian Mixture Models (GMM) supervised machine learning. Using this technique and gi multicolour photometric observations from the Dark Energy Survey (DES), near-IR JK photometry from the VISTA Hemisphere Survey (VHS) and WISE mid-IR photometry, we have identified a candidate system with two catalogue components with i_AB = 18.61 and i_AB = 20.44 comprising an elliptical galaxy and two blue point sources. Spectroscopic follow-up with NTT and the use of an archival AAT spectrum show that the point sources can be identified as a lensed quasar with an emission line redshift of z = 2.739 ± 0.003 and a foreground early-type galaxy with z = 0.400 ± 0.002.We model the system as a single isothermal ellipsoid and find the Einstein radius θ_E ~ 1.47 arcsec, enclosed mass M_enc ~ 4 × 10¹¹ M_⊙ and a time delay of ~52 d. The relatively wide separation, month scale time delay duration and high redshift make this an ideal system for constraining the expansion rate beyond a redshift of 1.

Original language	English
Pages (from-to)	4325-4334
Number of pages	10
Journal	Monthly Notices of the Royal Astronomical Society
Volume	465
Issue number	4
DOIs	https://doi.org/10.1093/mnras/stw2958
State	Published - Mar 11 2017

Funding

FO is supported jointly by CAPES (the Science without Borders programme) and the Cambridge Commonwealth Trust. RGM, CAL, MWA, MB, SLR acknowledge the support of UK Science and Technology Research Council (STFC). AJC acknowledges the support of a Raymond and Beverly Sackler visiting fellowship at the Institute of Astronomy. 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 FacilitiesCouncil of theUnitedKingdom, theHigher Education Funding Council for England, the NationalCenter 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, Fundaç ão 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 Inovaç ão, 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 (ETH) 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 Universit ät 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, TexasA&MUniversity, and the OzDES Membership Consortium. The DES data management system is supported by the National Science Foundation under Grant Number AST-1138766. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2012-39559, ESP2013-48274, FPA2013-47986, and Centro de Excelencia Severo Ochoa SEV-2012-0234. 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. The analysis presented here is based on observations obtained as part of the VISTA Hemisphere Survey, ESO Programme, 179.A-2010 (PI: McMahon) and ESO Programme 096.A-0411. This work was based in part on data acquired through the AustralianAstronomical Observatory, under programmesA/2013A/018 and A/2013B/001. This research made use of Astropy (Astropy Collaboration et al. 2013), a community-developed core PYTHON package for Astronomy (Astropy Collaboration, 2013). This research made use of OM105 mock catalogue of strong gravitational lenses and FO thanks Dr Phil Marshall for support and useful discussions.

Funders	Funder number
Centro de Excelencia Severo Ochoa	SEV-2012-0234
Collaborating Institutions are Argonne National Laboratory
Institut de Ciències de l'Espai
Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University
TexasA&MUniversity
UK Science and Technology Research Council
National Science Foundation	AST-1138766
U.S. Department of Energy
University of Illinois at Urbana-Champaign
Stanford University
Fermilab
Lawrence Berkeley National Laboratory
University of California, Santa Cruz
University of Pennsylvania
Ohio State University
University of Chicago
University of Michigan
University of Portsmouth
National Centre for Supercomputing Applications
Seventh Framework Programme
SLAC National Accelerator Laboratory
Science and Technology Facilities Council
Higher Education Funding Council for England
University College London
European Research Council	A/2013B/001, 240672, 2013, 306478, 291329
University of Nottingham
University of Sussex
University of Edinburgh
Deutsche Forschungsgemeinschaft
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Eidgenössische Technische Hochschule Zürich
Ministerio de Economía y Competitividad	FPA2013-47986, AYA2012-39559, ESP2013-48274
Cambridge Commonwealth Trust
Ministério da Ciência, Tecnologia e Inovação
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro
Financiadora de Estudos e Projetos
Seventh Framework Programme
Ludwig-Maximilians-Universität München
Ministry of Education and Science of Ukraine
Institut de Física d'Altes Energies

Keywords

Gravitational lensing: strong
Methods: observational
Methods: statistical
Quasars: general

Access to Document

10.1093/mnras/stw2958

Cite this

Ostrovski, F., McMahon, R. G., Connolly, A. J., Lemon, C. A., Auger, M. W., Banerji, M., Hung, J. M., Koposov, S. E., Lidman, C. E., Reed, S. L., Allam, S., Benoit-Lévy, A., Bertin, E., Brooks, D., Buckley-Geer, E., Rosell, A. C., Kind, M. C., Carretero, J., Cunha, C. E., ... Walker, A. R. (2017). VDES J2325-5229 a z = 2.7 gravitationally lensed quasar discovered using morphology-independent supervised machine learning. Monthly Notices of the Royal Astronomical Society, 465(4), 4325-4334. https://doi.org/10.1093/mnras/stw2958

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title = "VDES J2325-5229 a z = 2.7 gravitationally lensed quasar discovered using morphology-independent supervised machine learning",

abstract = "We present the discovery and preliminary characterization of a gravitationally lensed quasar with a source redshift zs = 2.74 and image separation of 2.9 arcsec lensed by a foreground zl = 0.40 elliptical galaxy. Since optical observations of gravitationally lensed quasars showthe lens system as a superposition of multiple point sources and a foreground lensing galaxy, we have developed a morphology-independent multi-wavelength approach to the photometric selection of lensed quasar candidates based on Gaussian Mixture Models (GMM) supervised machine learning. Using this technique and gi multicolour photometric observations from the Dark Energy Survey (DES), near-IR JK photometry from the VISTA Hemisphere Survey (VHS) and WISE mid-IR photometry, we have identified a candidate system with two catalogue components with iAB = 18.61 and iAB = 20.44 comprising an elliptical galaxy and two blue point sources. Spectroscopic follow-up with NTT and the use of an archival AAT spectrum show that the point sources can be identified as a lensed quasar with an emission line redshift of z = 2.739 ± 0.003 and a foreground early-type galaxy with z = 0.400 ± 0.002.We model the system as a single isothermal ellipsoid and find the Einstein radius θE ~ 1.47 arcsec, enclosed mass Menc ~ 4 × 1011 M⊙ and a time delay of ~52 d. The relatively wide separation, month scale time delay duration and high redshift make this an ideal system for constraining the expansion rate beyond a redshift of 1.",

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

author = "Fernanda Ostrovski and McMahon, {Richard G.} and Connolly, {Andrew J.} and Lemon, {Cameron A.} and Auger, {Matthew W.} and Manda Banerji and Hung, {Johnathan M.} and Koposov, {Sergey E.} and Lidman, {Christopher E.} and Reed, {Sophie L.} and Sahar Allam and Aur{\'e}lien Benoit-L{\'e}vy and Emmanuel Bertin and David Brooks and Elizabeth Buckley-Geer and Rosell, {Aurelio Carnero} and Kind, {Matias Carrasco} and Jorge Carretero and Cunha, {Carlos E.} and {da Costa}, {Luiz N.} and Shantanu Desai and Diehl, {H. Thomas} and Dietrich, {J{\"o}rg P.} and Evrard, {August E.} and Finley, {David A.} and Brenna Flaugher and Pablo Fosalba and Josh Frieman and Gerdes, {David W.} and Goldstein, {Daniel A.} and Daniel Gruen and Gruendl, {Robert A.} and Gaston Gutierrez and Klaus Honscheid and James, {David J.} and Kyler Kuehn and Nikolay Kuropatkin and Marcos Lima and Huan Lin and Maia, {Marcio A.G.} and Marshall, {Jennifer L.} and Paul Martini and Peter Melchior and Ramon Miquel and Ricardo Ogando and Malag{\'o}n, {Andr{\'e}s Plazas} and Kevin Reil and Kathy Romer and Eusebio Sanchez and Basilio Santiago and Vic Scarpine and Ignacio Sevilla-Noarbe and Marcelle Soares-Santos and Flavia Sobreira and Eric Suchyta and Gregory Tarle and Daniel Thomas and Tucker, {Douglas L.} and Walker, {Alistair R.}",

note = "Publisher Copyright: {\textcopyright} 2016 The Authors.",

year = "2017",

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day = "11",

doi = "10.1093/mnras/stw2958",

language = "English",

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pages = "4325--4334",

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

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Ostrovski, F, McMahon, RG, Connolly, AJ, Lemon, CA, Auger, MW, Banerji, M, Hung, JM, Koposov, SE, Lidman, CE, Reed, SL, Allam, S, Benoit-Lévy, A, Bertin, E, Brooks, D, Buckley-Geer, E, Rosell, AC, Kind, MC, Carretero, J, Cunha, CE, da Costa, LN, Desai, S, Diehl, HT, Dietrich, JP, Evrard, AE, Finley, DA, Flaugher, B, Fosalba, P, Frieman, J, Gerdes, DW, Goldstein, DA, Gruen, D, Gruendl, RA, Gutierrez, G, Honscheid, K, James, DJ, Kuehn, K, Kuropatkin, N, Lima, M, Lin, H, Maia, MAG, Marshall, JL, Martini, P, Melchior, P, Miquel, R, Ogando, R, Malagón, AP, Reil, K, Romer, K, Sanchez, E, Santiago, B, Scarpine, V, Sevilla-Noarbe, I, Soares-Santos, M, Sobreira, F, Suchyta, E, Tarle, G, Thomas, D, Tucker, DL & Walker, AR 2017, 'VDES J2325-5229 a z = 2.7 gravitationally lensed quasar discovered using morphology-independent supervised machine learning', Monthly Notices of the Royal Astronomical Society, vol. 465, no. 4, pp. 4325-4334. https://doi.org/10.1093/mnras/stw2958

TY - JOUR

T1 - VDES J2325-5229 a z = 2.7 gravitationally lensed quasar discovered using morphology-independent supervised machine learning

AU - Ostrovski, Fernanda

AU - McMahon, Richard G.

AU - Connolly, Andrew J.

AU - Lemon, Cameron A.

AU - Auger, Matthew W.

AU - Banerji, Manda

AU - Hung, Johnathan M.

AU - Koposov, Sergey E.

AU - Lidman, Christopher E.

AU - Reed, Sophie L.

AU - Allam, Sahar

AU - Benoit-Lévy, Aurélien

AU - Bertin, Emmanuel

AU - Brooks, David

AU - Buckley-Geer, Elizabeth

AU - Rosell, Aurelio Carnero

AU - Kind, Matias Carrasco

AU - Carretero, Jorge

AU - Cunha, Carlos E.

AU - da Costa, Luiz N.

AU - Desai, Shantanu

AU - Diehl, H. Thomas

AU - Dietrich, Jörg P.

AU - Evrard, August E.

AU - Finley, David A.

AU - Flaugher, Brenna

AU - Fosalba, Pablo

AU - Frieman, Josh

AU - Gerdes, David W.

AU - Goldstein, Daniel A.

AU - Gruen, Daniel

AU - Gruendl, Robert A.

AU - Gutierrez, Gaston

AU - Honscheid, Klaus

AU - James, David J.

AU - Kuehn, Kyler

AU - Kuropatkin, Nikolay

AU - Lima, Marcos

AU - Lin, Huan

AU - Maia, Marcio A.G.

AU - Marshall, Jennifer L.

AU - Martini, Paul

AU - Melchior, Peter

AU - Miquel, Ramon

AU - Ogando, Ricardo

AU - Malagón, Andrés Plazas

AU - Reil, Kevin

AU - Romer, Kathy

AU - Sanchez, Eusebio

AU - Santiago, Basilio

AU - Scarpine, Vic

AU - Sevilla-Noarbe, Ignacio

AU - Soares-Santos, Marcelle

AU - Sobreira, Flavia

AU - Suchyta, Eric

AU - Tarle, Gregory

AU - Thomas, Daniel

AU - Tucker, Douglas L.

AU - Walker, Alistair R.

PY - 2017/3/11

Y1 - 2017/3/11

N2 - We present the discovery and preliminary characterization of a gravitationally lensed quasar with a source redshift zs = 2.74 and image separation of 2.9 arcsec lensed by a foreground zl = 0.40 elliptical galaxy. Since optical observations of gravitationally lensed quasars showthe lens system as a superposition of multiple point sources and a foreground lensing galaxy, we have developed a morphology-independent multi-wavelength approach to the photometric selection of lensed quasar candidates based on Gaussian Mixture Models (GMM) supervised machine learning. Using this technique and gi multicolour photometric observations from the Dark Energy Survey (DES), near-IR JK photometry from the VISTA Hemisphere Survey (VHS) and WISE mid-IR photometry, we have identified a candidate system with two catalogue components with iAB = 18.61 and iAB = 20.44 comprising an elliptical galaxy and two blue point sources. Spectroscopic follow-up with NTT and the use of an archival AAT spectrum show that the point sources can be identified as a lensed quasar with an emission line redshift of z = 2.739 ± 0.003 and a foreground early-type galaxy with z = 0.400 ± 0.002.We model the system as a single isothermal ellipsoid and find the Einstein radius θE ~ 1.47 arcsec, enclosed mass Menc ~ 4 × 1011 M⊙ and a time delay of ~52 d. The relatively wide separation, month scale time delay duration and high redshift make this an ideal system for constraining the expansion rate beyond a redshift of 1.

AB - We present the discovery and preliminary characterization of a gravitationally lensed quasar with a source redshift zs = 2.74 and image separation of 2.9 arcsec lensed by a foreground zl = 0.40 elliptical galaxy. Since optical observations of gravitationally lensed quasars showthe lens system as a superposition of multiple point sources and a foreground lensing galaxy, we have developed a morphology-independent multi-wavelength approach to the photometric selection of lensed quasar candidates based on Gaussian Mixture Models (GMM) supervised machine learning. Using this technique and gi multicolour photometric observations from the Dark Energy Survey (DES), near-IR JK photometry from the VISTA Hemisphere Survey (VHS) and WISE mid-IR photometry, we have identified a candidate system with two catalogue components with iAB = 18.61 and iAB = 20.44 comprising an elliptical galaxy and two blue point sources. Spectroscopic follow-up with NTT and the use of an archival AAT spectrum show that the point sources can be identified as a lensed quasar with an emission line redshift of z = 2.739 ± 0.003 and a foreground early-type galaxy with z = 0.400 ± 0.002.We model the system as a single isothermal ellipsoid and find the Einstein radius θE ~ 1.47 arcsec, enclosed mass Menc ~ 4 × 1011 M⊙ and a time delay of ~52 d. The relatively wide separation, month scale time delay duration and high redshift make this an ideal system for constraining the expansion rate beyond a redshift of 1.

KW - Gravitational lensing: strong

KW - Methods: observational

KW - Methods: statistical

KW - Quasars: general

UR - http://www.scopus.com/inward/record.url?scp=85014823860&partnerID=8YFLogxK

U2 - 10.1093/mnras/stw2958

DO - 10.1093/mnras/stw2958

M3 - Article

AN - SCOPUS:85014823860

SN - 0035-8711

VL - 465

SP - 4325

EP - 4334

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 4

ER -

VDES J2325-5229 a z = 2.7 gravitationally lensed quasar discovered using morphology-independent supervised machine learning

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