Models of the strongly lensed quasar DES J0408−5354

A. Agnello , H. Lin , L. Buckley-Geer , T. Treu , V. Bonvin , F. Courbin , C. Lemon , T. Morishita , A. Amara , M.W. Auger , S. Birrer , J. Chan , T. Collett , A. More , C.D. Fassnacht , J. Frieman , P.J. Marshall , R.G. Mcmahon , G. Meylan , S.H. Suyu , F. Castander , D. Finley , A. Howell , C. Kochanek , M. Makler , P. Martini , N. Morgan , B. Nord , F. Ostrovski , P. Schechter , D. Tucker , R. Wechsler , T.M.C. Abbott , F.B. Abdalla , S. Allam , A. Benoit-Lévy (1) , E. Bertin (1) , D. Brooks , D.L. Burke , A. Carnero Rosell , M. Carrasco Kind , J. Carretero , M. Crocce , C.E. Cunha , C.B. d'Andrea , L.N. da Costa , S. Desai , J.P. Dietrich , T.F. Eifler , B. Flaugher , P. Fosalba , J. García-Bellido , E. Gaztanaga , M.S. Gill , D.A. Goldstein , D. Gruen , R.A. Gruendl , J. Gschwend , G. Gutierrez , K. Honscheid , D.J. James , K. Kuehn , N. Kuropatkin , T.S. Li , M. Lima , M.A.G. Maia , M. March , J.L. Marshall , P. Melchior , F. Menanteau , R. Miquel , R.L.C. Ogando , A.A. Plazas , A.K. Romer , E. Sanchez , R. Schindler , M. Schubnell , I. Sevilla-Noarbe , M. Smith , R.C. Smith , F. Sobreira , E. Suchyta , M.E.C. Swanson , G. Tarle , D. Thomas , A.R. Walker

1 IAP - Institut d'Astrophysique de Paris

We present detailed modelling of the recently discovered, quadruply lensed quasar J0408−5354, with the aim of interpreting its remarkable configuration: besides three quasar images (A,B,D) around the main deflector (G1), a fourth image (C) is significantly reddened and dimmed by a perturber (G2) which is not detected in the Dark Energy Survey imaging data. From lens models incorporating (dust-corrected) flux ratios, we find a perturber Einstein radius 0.04 arcsec ≲ R_E, G2 ≲ 0.2 arcsec and enclosed mass (R_E, G2) ≲ 1.0 × 10^10 M_⊙. The main deflector has stellar mass $$\log _{10}(M_{\star }/\mathrm{M}_{{\odot }})=11.49^{+0.46}_{-0.32}$$, a projected mass M_p(R_E, G1) ≈ 6 × 10^11 M_⊙ within its Einstein radius R_E, G1 = (1.85 ± 0.15) arcsec and predicted velocity dispersion 267–280 km s^−1. Follow-up images from a companion monitoring campaign show additional components, including a candidate second source at a redshift between the quasar and G1. Models with free perturbers, and dust-corrected and delay-corrected flux ratios, are also explored. The predicted time-delays (Δt_AB = (135.0 ± 12.6) d, Δt_BD = (21.0 ± 3.5) d) roughly agree with those measured, but better imaging is required for proper modelling and comparison. We also discuss some lessons learnt from J0408−5354  on lensed quasar finding strategies, due to its chromaticity and morphology.

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

Domaines: Astrophysique [astro-ph]

A. Agnello, H. Lin, L. Buckley-Geer, T. Treu, V. Bonvin, et al.. Models of the strongly lensed quasar DES J0408−5354. Monthly Notices of the Royal Astronomical Society, 2017, 472 (4), pp.4038-4050. ⟨10.1093/mnras/stx2242⟩. ⟨hal-01645195⟩