A Lensing View On The Fundamental Plane
  For lensing galaxies we introduce a formal velocity dispersion sigma_lens,
based on enclosed mass and the virial theorem. This is calculated from an
ensemble of pixelated lens models, and found to be fairly model independent. A
sample of 18 well-known early-type lensing galaxies and two clusters is found
to be consistent with the equality of sigma_lens and the kinematic velocity
dispersion sigma_obs. Both the early-type lensing galaxies and the clusters can
thus be determined as being virialized. In a second step we calculate the
I-band luminosity and the total mass content for the sample of lensing
galaxies, which enables us to analyze the mass-to-light relation L ~ M^a. We
determine a = 0.70 +/- 0.08, excluding constant M/L and consistent with
previous studies of the Fundamental Plane. Additionally we verify that this
relation does not extrapolate to clusters, which have a much higher M/L. The
sample used for this analysis comprises 9 lensing galaxies from the Sloan Lens
ACS Survey (SLACS) and another 9 from the CfA-Arizona Space Telescope LEns
Survey (CASTLES) as well as the lensing clusters ACO 1689 and ACO 2667.
