DES meets Gaia: discovery of strongly lensed quasars from a multiplet search

A. Agnello , H. Lin , N. Kuropatkin , E. Buckley-Geer , T. Anguita , P.L. Schechter , T. Morishita , V. Motta , K. Rojas , T. Treu , A. Amara , M.W. Auger , F. Courbin , C.D. Fassnacht , J. Frieman , A. More , P.J. Marshall , R.G. Mcmahon , G. Meylan , S.H. Suyu , K. Glazebrook , N. Morgan , B. Nord , T.M.C. Abbott , F.B. Abdalla , J. Annis , K. Bechtol , A. Benoit-Lévy (1) , E. Bertin (1) , R.A. Bernstein , D. Brooks , D.L. Burke , A. Carnero Rosell , J. Carretero , C.E. Cunha , C.B. d'Andrea , L.N. da Costa , S. Desai , A. Drlica-Wagner , T.F. Eifler , B. Flaugher , J. García-Bellido , E. Gaztanaga , D.W. Gerdes , D. Gruen , R.A. Gruendl , J. Gschwend , G. Gutierrez , K. Honscheid , D.J. James , K. Kuehn , O. Lahav , M. Lima , M.A.G. Maia , M. March , F. Menanteau , R. Miquel , R.L.C. Ogando , A.A. Plazas , E. Sanchez , V. Scarpine , R. Schindler , M. Schubnell , I. Sevilla-Noarbe , M. Smith , M. Soares-Santos , F. Sobreira , E. Suchyta , M.E.C. Swanson , G. Tarle , D. Tucker , R. Wechsler

1 IAP - Institut d'Astrophysique de Paris

We report the discovery, spectroscopic confirmation, and first lens models of the first, strongly lensed quasars from a combined search in WISE and Gaia-DR1 over the DES footprint. Their Einstein radii span a range between ≈2.0 arcsec and ≈0.4 arcsec. Two of these (WGD2038-4008, RA = 20:38:02.65, Dec. = −40:08:14.64; WGD2021-4115, RA = 20:21:39.45, Dec. = −41:15:57.11) also have confirmed deflector redshifts. The four-image lens WGD2038-4008, with source and deflector redshifts _s = 0.777 ± 0.001 and = 0.230 ± 0.002, respectively, has a deflector with radius R_eff ≈ 3.4 arcsec, stellar mass |$\log (M_{\star }/M_{\odot })=11.64^{+0.20}_{-0.43}$|⁠, and extended isophotal shape variation. Simple lens models yield Einstein radii R_E = (1.30 ± 0.04) arcsec, axis ratio q = 0.75 ± 0.1 (compatible with that of the starlight) and considerable shear-ellipticity degeneracies. The two-image lens WGD2021-4115 has z_s = 1.390 ± 0.001 and z_l = 0.335 ± 0.002, and Einstein radius R_E = (1.1 ± 0.1) arcsec, but higher-resolution imaging is needed to accurately separate the deflector and faint quasar image. Analogous lens model degeneracies hold for the other six lenses (J0146-1133, J0150-4041, J0235-2433, J0245-0556, J0259-2338, and J0508-2748) shown in this paper.

Mots clés: gravitational lensing: strong; methods: statistical; techniques: image processing; surveys

Domaines: Astrophysique [astro-ph]

A. Agnello, H. Lin, N. Kuropatkin, E. Buckley-Geer, T. Anguita, et al.. DES meets Gaia: discovery of strongly lensed quasars from a multiplet search. Mon.Not.Roy.Astron.Soc., 2018, 479 (4), pp.4345-4354. ⟨10.1093/mnras/sty1419⟩. ⟨hal-01863636⟩