Quasar lenses and pairs in the VST-ATLAS and Gaia

A. Agnello, P. L. Schechter, N. D. Morgan, T. Treu, C. Grillo, D. Malesani, T. Anguita, Y. Apostolovski, C. E. Rusu, V. Motta, K. Rojas, B. Chehade, T. Shanks

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


We report on discovery results from a quasar lens search in the ATLAS-DR3 public footprint. Spectroscopic follow-up campaigns, conducted at the 2.6 m Nordic Optical Telescope (La Palma) and 3.6mNew Technology Telescope (La Silla) in 2016, yielded seven pairs of quasars exhibiting the same lines at the same redshift and monotonic flux ratios with wavelength (hereafter NIQs, nearly identical quasar pairs). Magellan spectra of A0140-1152 (01h40m03.s0-11d52m19.s0, zs = 1.807) confirm it as a lens with deflector at zl = 0.277 and Einstein radius θE = (0.73 ± 0.02) arcsec. Follow-up imaging of the NIQ A2213-2652 (22h13m38.s4-26d52m27.s1) reveals the deflector galaxy and confirms it as a lens. We show the use of spatial resolution from the Gaia mission to select lenses and list additional systems from a WISEGaia- ATLAS search, yielding three additional lenses (02h35m27.s4-24d33m13.s2, 02h59m33s- 23d38m01.s8, 01h46m32.s9-11d33m39.s0). The overall sample consists of 11 lenses/NIQs, plus three lenses known before 2016, over the ATLAS-DR3 footprint (≈3500 deg2). Finally, we discuss future prospects for objective classification of pair/NIQ/contaminant spectra.

Original languageEnglish
Pages (from-to)2086-2096
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Publication statusPublished - 1 Apr 2018


  • Gravitational lensing: strong
  • Methods: statistical
  • Quasars: general
  • Surveys
  • Techniques: image processing

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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