The SAMI Pilot Survey: The Fundamental and Mass Planes in Three
  Low-Redshift Clusters
  Using new integral field observations of 106 galaxies in three nearby
clusters we investigate how the intrinsic scatter of the Fundamental Plane
depends on the way in which the velocity dispersion and effective radius are
measured. Our spatially resolved spectroscopy, combined with a cluster sample
with negligible relative distance errors allows us to derive a Fundamental
Plane with minimal systematic uncertainties. From the apertures we tested, we
find that velocity dispersions measured within a circular aperture with radius
equal to one effective radius minimises the intrinsic scatter of the
Fundamental Plane. Using simple yet powerful Jeans dynamical models we
determine dynamical masses for our galaxies. Replacing luminosity in the
Fundamental Plane with dynamical mass, we demonstrate that the resulting Mass
Plane has further reduced scatter, consistent with zero intrinsic scatter.
Using these dynamical models we also find evidence for a possibly non-linear
relationship between dynamical mass-to-light ratio and velocity dispersion.
