Quasar lenses and pairs in the VST-ATLAS and Gaia

Indexación: Scopus.The data presented here were obtained in part with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA) under a joint agreement with the University of Copenhagen and NOTSA. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. TT acknowledges support from NSF through grant AST-1450141, and from the Packard Foundation through a Packard Research Fellowship. VM acknowledges support from Centro de Astrofísica de Valparaíso. TA and YA acknowledge support by proyecto FONDECYT 11130630 and by the Ministry for the Economy, Development, and Tourism's Programa Inicativa Científica Milenio through grant IC 12009, awarded to The Millennium Institute of Astrophysics (MAS). DM acknowledges financial support from the Instrument Center for Danish Astrophysics (IDA). KR is supported by Becas de Doctorado Nacional CONICYT 2017. AA is grateful to Mike Read for explanations on the ATLAS releases and support with the queries, to Alain Smette and Dominique Sluse for advice on quasar pairs, as well as to Johan Fynbo for sharing part of the NOT guaranteed time in February 2016 for this project. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.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. © 2017 The Authors.https://academic.oup.com/mnras/article/475/2/2086/473936