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

In this paper, 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 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 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 themore » Einstein radius θ E ~ 1.47 arcsec, enclosed mass M enc ~ 4 × 10 11 M 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.« less
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [4] ;  [2] ;  [5] ;  [4] ;  [6] ;  [2] ;  [7] ;  [8] ;  [9] ;  [10] ;  [7] ;  [11] ;  [12] ;  [13] ;  [14] ;  [11] more »;  [15] ;  [7] ;  [15] ;  [16] ;  [7] ;  [7] ;  [17] ;  [18] ;  [19] ;  [20] ;  [21] ;  [12] ;  [7] ;  [22] ;  [23] ;  [24] ;  [7] ;  [25] ;  [7] ;  [11] ;  [26] ;  [27] ;  [28] ;  [29] ;  [11] ;  [30] ;  [31] ;  [32] ;  [33] ;  [34] ;  [7] ;  [33] ;  [7] ;  [35] ;  [36] ;  [19] ;  [37] ;  [7] ;  [23] « less
  1. Univ. of Cambridge (United Kingdom). Inst. of Astronomy. Kavli Inst. for Cosmology; CAPES Foundation, Brasilia (Brazil)
  2. Univ. of Cambridge (United Kingdom). Inst. of Astronomy. Kavli Inst. for Cosmology
  3. Univ. of Cambridge (United Kingdom). Inst. of Astronomy; Univ. of Washington, Seattle, WA (United States). Dept. of Astronomy
  4. Univ. of Cambridge (United Kingdom). Inst. of Astronomy
  5. Univ. of Cambridge (United Kingdom). Inst. of Astronomy. Centre for Mathematical Sciences. Dept. of Applied Mathematics and Theoretical Physics (DAMTP)
  6. Univ. of Wollongong, NSW (Australia). School of Physics; Australian Astronomical Observatory, North Ryde, NSW (Australia)
  7. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
  8. National Centre for Scientific Research (CNRS), Paris (France). Inst. of Astrophysics; Univ. College London (United Kingdom). Dept. of Physics and Astronomy; Sorbonne Univ., Paris (France). Inst. of Astrophysics
  9. National Centre for Scientific Research (CNRS), Paris (France). Inst. of Astrophysics; Sorbonne Univ., Paris (France). Inst. of Astrophysics
  10. Univ. College London (United Kingdom). Dept. of Physics and Astronomy
  11. Inter-Institutional Astronomy Lab (LIneA), Rio de Janeiro (Brazil); National Observatory, Rio de Janeiro (Brazil)
  12. Univ. of Illinois, Urbana, IL (United States). Dept. of Astronomy; National Center for Supercomputing Applications (NCSA), Urbana, IL (United States)
  13. IEEC-CSIC, Barcelona (Spain). Inst. of Space Sciences; The Barcelona Inst. of Science and Technology, Barcelona (Spain). Inst. of High Energy Physics
  14. Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology
  15. Excellence Cluster Universe, Garching (Germany); Ludwig Maximilian Univ., Munich (Germany). Faculty of Physics
  16. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Astronomy. Dept. of Physics
  17. IEEC-CSIC, Barcelona (Spain). Inst. of Space Sciences
  18. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Univ. of Chicago, IL (United States). Kavli Inst. for Cosmological Physics
  19. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Physics
  20. Univ. of California, Berkeley, CA (United States). Dept. of Astronomy; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  21. Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology; SLAC National Accelerator Lab., Menlo Park, CA (United States)
  22. The Ohio State Univ., Columbus, OH (United States). Center for Cosmology and Astro-Particle Physics. Dept. of Physics
  23. National Optical Astronomy Observatory, La Serena (Chile). Cerro Tololo Inter-American Observatory
  24. Australian Astronomical Observatory, North Ryde, NSW (Australia)
  25. Inter-Institutional Astronomy Lab (LIneA), Rio de Janeiro (Brazil); Univ. of Sao Paulo (Brazil). Inst. of Physics. Dept. of Mathematical Physics
  26. Texas A & M Univ., College Station, TX (United States). George P. and Cynthia Woods Mitchell Inst. for Fundamental Physics and Astronomy. Dept. of Physics and Astronomy
  27. The Ohio State Univ., Columbus, OH (United States). Center for Cosmology and Astro-Particle Physics. Dept. of Astronomy
  28. Princeton Univ., NJ (United States). Dept. of Astrophysical Sciences
  29. The Barcelona Inst. of Science and Technology, Barcelona (Spain). Inst. of High Energy Physics; Catalan Institution for Research and Advanced Studies, Barcelona (Spain)
  30. California Inst. of Technology (CalTech), Pasadena, CA (United States). Jet Propulsion Lab.
  31. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  32. Univ. of Sussex, Brighton (United Kingdom). Dept. of Physics and Astronomy
  33. Center for Energy, Environmental and Technological Research (CIEMAT), Madrid (Spain)
  34. Inter-Institutional Astronomy Lab (LIneA), Rio de Janeiro (Brazil); Federal Univ. of Rio Grande do Sul (UFRGS), Porto Alegre (Brazil). Inst. of Physics
  35. Inter-Institutional Astronomy Lab (LIneA), Rio de Janeiro (Brazil); Sao Paulo State Univ. (Brazil). Inst. of Theoretical Physics. ICTP South American Inst. for Fundamental Research
  36. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Computer Science and Mathematics Division
  37. Univ. of Portsmouth (United Kingdom). Inst. of Cosmology and Gravitation
Publication Date:
Report Number(s):
arXiv:1607.01391; FERMILAB-PUB-16-220
Journal ID: ISSN 0035-8711; KJ0402000; KJ0503000; ERKJ311; ERKJEPM; TRN: US1701242
Grant/Contract Number:
AC05-00OR22725; AST-1138766; AYA2012-39559; ESP2013-48274; FPA2013-47986; SEV-2012-0234; 240672; 291329; 306478; A/2013A/018; A/2013B/001; AC02-76SF00515; AC02-07CH11359
Type:
Accepted Manuscript
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Volume: 465; Journal Issue: 4; Journal ID: ISSN 0035-8711
Publisher:
Royal Astronomical Society
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Orgs:
DES
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; strong gravitational lensing; quasars; observational methods; statistical methods
OSTI Identifier:
1340464
Alternate Identifier(s):
OSTI ID: 1353198; OSTI ID: 1353386