Comparing Lensing and Stellar Orbital Models of a Nearby Massive
  Strong-Lens Galaxy
  Exploiting the relative proximity of the nearby strong-lens galaxy SNL-1, we
present a critical comparison of the mass estimates derived from independent
modelling techniques. We fit triaxial orbit-superposition dynamical models to
spatially-resolved stellar kinematics, and compare to the constraints derived
from lens modelling of high-resolution photometry. From the dynamical model, we
measure the total (dynamical) mass enclosed within a projected aperture of
radius the Einstein radius to be $\log_{10} M_{\mathrm{Ein.}} = 11.00 \pm
0.02$, which agrees with previous measurements from lens modelling to within
$5\%$. We then explore the intrinsic (de-projected) properties of the
best-fitting dynamical model. We find that SNL-1 has approximately-constant,
intermediate triaxiality at all radii. It is oblate-like in the inner regions
(around the Einstein radius) and tends towards spherical at larger radii. The
stellar velocity ellipsoid gradually transforms from isotropic in the very
central regions to radially-biased in the outskirts. We find that SNL-1 is
dynamically consistent with the broader galaxy population, as measured by the
relative fraction of orbit `temperatures' compared to the CALIFA survey. On the
mass--size plane, SNL-1 occupies the most-compact edge given its mass, compared
to both the MaNGA and SAMI surveys. Finally, we explore how the observed
lensing configuration is affected by the orientation of the lens galaxy. We
discuss the implications of such detailed models on future combined lensing and
dynamical analyses.
