VDES J2325-5229 a z = 2.7 gravitationally lensed quasar discovered using morphology-independent supervised machine learning [electronic resource].
- Washington, D.C. : United States. Dept. of Energy. Office of Science, 2016.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
- Physical Description:
- pages 4,325-4,334 : digital, PDF file
- Additional Creators:
- Oak Ridge National Laboratory
United States. Department of Energy. Office of Science
United States. Department of Energy. Office of Scientific and Technical Information
- In this paper, we present the discovery and preliminary characterization of a gravitationally lensed quasar with a source redshift z<sub>s</sub> = 2.74 and image separation of 2.9 arcsec lensed by a foreground z<sub>l</sub> = 0.40 elliptical galaxy. Since optical observations of gravitationally lensed quasars show the 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<sub>AB</sub> = 18.61 and i<sub>AB</sub> = 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<sub>E</sub> ~ 1.47 arcsec, enclosed mass M<sub>enc</sub> ~ 4 × 10<sup>11</sup> M<sub>⊙</sub> and a time delay of ~52 d. Finally, 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.
- Published through SciTech Connect.
Monthly Notices of the Royal Astronomical Society 465 4 ISSN 0035-8711 AM
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; et al.
- Funding Information:
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