COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses VIII.
  Deconvolution of high resolution near-IR images and simple mass models for 7
  gravitationally lensed quasars
  We apply the iterative MCS deconvolution method (ISMCS) to near-IR HST
archives data of seven gravitationally lensed quasars currently monitored by
the COSMOGRAIL collaboration: HE 0047-1756, RX J1131-1231, SDSS J1138+0314,
SDSS J1155+6346, SDSS J1226-0006, WFI J2026-4536 and HS 2209+1914. In doing so,
we obtain relative positions for the lensed images and shape parameters for the
light distribution of the lensing galaxy in each system. The lensed image
positions are derived with 1-2 mas accuracy. To predict time delays and to test
the ability of simple mass models to reproduce the observed configuration,
isothermal and de Vaucouleurs mass models are calculated for the whole sample
using state-of-the-art modeling techniques. The effect of the lens environment
on the lens mass models is taken into account with a shear term. Doubly imaged
quasars are equally well fitted by each of these models. A large amount of
shear is necessary to reproduce SDSS J1155+6346 and SDSS J1226-006. In the
latter case, we identify a nearby galaxy as the dominant source of shear. The
quadruply imaged quasar SDSS J1138+0314 is well reproduced by simple lens
models, which is not the case for the two other quads, RX J1131-1231 and WFI
J2026-4536. This might be the signature of astrometric perturbations due to
massive substructures in the lensing galaxy unaccounted for by the models.
Other possible explanations are also presented.
