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Quasar lenses and pairs in the VST-ATLAS and Gaia.

Agnello, A. and Schechter, P. L. and Morgan, N. D. and Treu, T. and Grillo, C. and Malesani, D. and Anguita, T. and Apostolovski, Y. and Rusu, C. E. and Motta, V. and Rojas, K. and Chehade, B. and Shanks, T. (2018) 'Quasar lenses and pairs in the VST-ATLAS and Gaia.', Monthly notices of the Royal Astronomical Society., 475 (2). pp. 2086-2096.


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 3.6 m New 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 s. 0–11d52m19 s. 0, 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 s. 4–26d52m27 s. 1) 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 WISE-Gaia-ATLAS search, yielding three additional lenses (02h35m27 s. 4–24d33m13 s. 2, 02h59m33s–23d38m01 s. 8, 01h46m32 s. 9–11d33m39 s. 0). 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.

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Publisher statement:This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:08 December 2017
Date deposited:29 March 2018
Date of first online publication:13 December 2017
Date first made open access:29 March 2018

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