Suchergebnisse

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) ; Cambridge Commonwealth Trust ; UK Science and Technology Research Council (STFC) ; Raymond and Beverly Sackler visiting fellowship at the Institute of Astronomy ; U.S. Department of Energy ; U.S. National Science Foundation ; Ministry of Science and Education of Spain ; Science and Technology Facilities Council of the United Kingdom ; Higher Education Funding Council for England ; National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign ; Kavli Institute of Cosmological Physics at the University of Chicago ; Center for Cosmology and Astro-Particle Physics at the Ohio State University ; Mitchell Institute for Fundamental Physics and Astronomy at Texas AM University ; Financiadora de Estudos e Projetos ; Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) ; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) ; Ministerio da Ciencia, Tecnologia e Inovacao ; Deutsche Forschungsgemeinschaft ; University of California at Santa Cruz ; University of Cambridge ; Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas-Madrid ; University of Chicago ; University College London ; DES-Brazil Consortium ; University of Edinburgh ; Eidgenossische Technische Hochschule (ETH) Zurich ; Fermi National Accelerator Laboratory ; University of Illinois at Urbana-Champaign ; Institut de Ciencies de l'Espai (IEEC/CSIC) ; Institut de Fisica d'Altes Energies ; Lawrence Berkeley National Laboratory ; Ludwig-Maximilians Universitar Munchen ; University of Michigan ; National Optical Astronomy Observatory ; University of Nottingham ; Ohio State University ; University of Pennsylvania ; University of Portsmouth ; SLAC National Accelerator Laboratory ; Stanford University ; University of Sussex ; Texas AM University ; OzDES Membership Consortium ; National Science Foundation ; MINECO ; Centro de Excelencia Severo Ochoa ; European Research Council under the European Union ; ESO ; Australian Astronomical Observatory ; ICREA ; Science and Technology Facilities Council ; National Science Foundation: AST-1138766 ; MINECO: AYA2012-39559 ; MINECO: ESP-201348274 ; MINECO: FPA2013-47986 ; Centro de Excelencia Severo Ochoa: SEV-2012-0234 ; European Research Council under the European Union: 240672 ; European Research Council under the European Union: 291329 ; European Research Council under the European Union: 306478 ; ESO: 179.A-2010 ; ESO: 096.A-0411 ; Australian Astronomical Observatory: A/2013A/018 ; Australian Astronomical Observatory: A/2013B/001 ; Science and Technology Facilities Council: ST/N004493/1 ; Science and Technology Facilities Council: ST/M003914/1 ; Science and Technology Facilities Council: ST/K004182/1 ; 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 theta(E) similar to 1.47 arcsec, enclosed mass M-enc similar to 4 x 10(11) M-circle dot and a time delay of similar to 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.