Models of the strongly lensed quasar DES J0408-5354
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2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. 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 RE, G2 0.2 arcsec and enclosed mass Mp(RE, G2) 1.0 1010 MO. The main deflector has stellar mass log10(M*/MO) = 11.49-0.32+0.46, a projected mass Mp(RE, G1) 6 1011 MO within its Einstein radius RE, 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 (tAB = (135.0 12.6) d, tBD = (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.