The STRong lensing Insights into the Dark Energy Survey (STRIDES) 2017/2018 follow-up campaign: Discovery of 10 lensed quasars and 10 quasar pairs ...

• Main Authors: Lemon, C, Auger, MW, McMahon, R, Anguita, T, Apostolovski, Y, Chen, GC-F, Fassnacht, CD, Melo, A, Motta, V, Shajib, A, Treu, T, Agnello, A, Buckley-Geer, E, Schechter, PL, Birrer, S, Collett, T, Courbin, F, Rusu, CE, Abbott, TMC, Allam, S, Annis, J, Avila, S, Bertin, E, Brooks, D, Burke, DL, Rosell, A Carnero, Kind, M Carrasco, Carretero, J, Costanzi, M, Costa, LN Da, Vicente, J De, Desai, S, Eifler, TF, Flaugher, B, Frieman, J, García-Bellido, J, Gaztanaga, E, Gerdes, DW, Gruen, D, Gruendl, RA, Gschwend, J, Gutierrez, G, Honscheid, K, James, DJ, Kim, A, Krause, E, Kuehn, K, Kuropatkin, N, Lahav, O, Lima, M
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University Press 2020
• Subjects: astro-ph.GA; sami
• Online Access: https://dx.doi.org/10.17863/cam.52401; https://www.repository.cam.ac.uk/handle/1810/305316

We report the results of the STRong lensing Insights from the Dark Energy Survey (STRIDES) follow-up campaign of the late 2017/early 2018 season. We obtained spectra of 65 lensed quasar candidates either with EFOSC2 on the NTT or ESI on Keck, which confirm 10 new gravitationally lensed quasars and 10 quasar pairs with similar spectra, but which do not show a lensing galaxy in DES images. Eight lensed quasars are doubly imaged with source redshifts between 0.99 and 2.90, one is triply imaged by a group (DESJ0345-2545, $z=1.68$), and one is quadruply imaged (quad: DESJ0053-2012, $z=3.8$). Singular isothermal ellipsoid models for the doubles, based on high-resolution imaging from SAMI on SOAR or NIRC2 on Keck, give total magnifications between 3.2 and 5.6, and Einstein radii between 0.49 and 1.97 arcseconds. After spectroscopic follow-up, we extract multi-epoch $grizY$ photometry of confirmed lensed quasars and contaminant quasar+star pairs from the first 4 years of DES data using parametric multi-band ...