Gaia DR2 Gravitational Lens Systems I: New lensed quasar candidates around known quasars

Abstract

Context. Strong gravitationally lensed quasars are among the most interesting and useful observable extragalactic phenomena. Because their study constitutes a unique tool in various fields of astronomy, they are highly sought, not without difficulty. Indeed, even in this era of all-sky surveys, their recognition remains a great challenge, with barely a few hundred currently known systems. Aims. In this work we aim to detect new strongly lensed quasar candidates in the recently published Gaia Data Release 2 (DR2), which is the highest spatial resolution astrometric and photometric all-sky survey, attaining effective resolutions from 0.4" to 2.2". Methods. We cross-matched a merged list of quasars and candidates with the Gaia DR2 and found 1,839,143 counterparts within 0.5". We then searched matches with more than two Gaia DR2 counterparts within 6". We further narrowed the resulting list using astrometry and photometry compatibility criteria between the Gaia DR2 counterparts. A supervised machine learning method, Extremely Randomized Trees, is finally adopted to assign to each remaining system a probability of being lensed. Results. We report the discovery of three quadruply-imaged quasar candidates that are fully detected in Gaia DR2. These are the most promising new quasar lens candidates from Gaia DR2 and a simple singular isothermal ellipsoid lens model is able to reproduce their image positions to within $\sim$1 mas. This letter demonstrates the gravitational lens discovery potential of Gaia.

arXiv comment4 pages, 1 figure, 2 tables - to be submitted to A&A Letters - Comments are very welcome

References in corpus (14)

• Gaia Data Release 2. Summary of the contents and survey properties
• The Gaia mission
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• Gaia Data Release 2: Photometric content and validation
• The Sloan Digital Sky Survey Quasar Catalog: twelfth data release
• H0LiCOW I. $H_0$ Lenses in COSMOGRAIL's Wellspring: Program Overview
• Flux ratios as a probe of dark substructures in quadruple-image gravitational lenses
• Cosmology with Strong Lensing Systems
• Effects of Triaxiality on the Statistics of Large-Separation Gravitational Lenses
• DES meets Gaia: discovery of strongly lensed quasars from a multiplet search
• The ESA Gaia Archive: Data Release 1
• Pushing the limits of the Gaia space mission by analyzing galaxy morphology
• Detection of Galaxies with Gaia
• Gaia GraL II - Gaia DR2 Gravitational Lens Systems: The Known Multiply Imaged Quasars

Cited by in corpus (6)

• Gravitationally lensed quasars in Gaia: III. 22 new lensed quasars from Gaia Data Release 2
• The STRong lensing Insights into the Dark Energy Survey (STRIDES) 2016 follow-up campaign. I. Overview and classification of candidates selected by two techniques
• Survey of Gravitationally-lensed Objects in HSC Imaging (SuGOHI). IV. Lensed quasar search in the HSC survey
• Gaia GraL: Gaia DR2 Gravitational Lens Systems. VI. Spectroscopic Confirmation and Modeling of Quadruply-Imaged Lensed Quasars
• Astrometric requirements for strong lensing time-delay cosmography
• Galaxy-lens determination of $H_0$: the effect of the ellipse+shear modeling assumption