Dissecting the 3D structure of elliptical galaxies with gravitational
  lensing and stellar kinematics
  The combination of strong gravitational lensing and stellar kinematics
provides a powerful and robust method to investigate the mass and dynamical
structure of early-type galaxies. We demonstrate this approach by analysing two
massive ellipticals from the XLENS Survey for which both high-resolution HST
imaging and X-Shooter spectroscopic observations are available. We adopt a
flexible axisymmetric two-component mass model for the lens galaxies,
consisting of a generalised NFW dark halo and a realistic self-gravitating
stellar mass distribution. For both systems, we put constraints on the dark
halo inner structure and flattening, and we find that they are dominated by the
luminous component within one effective radius. By comparing the tight
inferences on the stellar mass from the combined lensing and dynamics analysis
with the values obtained from stellar population studies, we conclude that both
galaxies are characterised by a Salpeter-like stellar initial mass function.
