Authors: Alister Graham & Matthew Colless
Abstract:
We examine the influence of broken structural homology upon the Fundamental
Plane (FP).
We fit the Sersic R{1/n} law, being the generalized R{1/4} law,
where `n' is a free parameter that accommodates structural
differences between different galaxies. The galaxy light
profiles show a trend of systematic departures from the de Vaucouleurs
R{1/4} law, such that the larger galaxies have less curvature in their
profiles than the R{1/4} profile and the smaller galaxies have greater
curvature, as found by Caon, Capaccioli & D'Onofrio (1993) and Graham et al.
(1996).
This results in the effective half-light radii, Re, and the mean
surface brightness within these radii,
,
having systematic biases if obtained from the R{1/4}
law. The observed range in structural shapes implies a corresponding range
in galaxy dynamics required to support the observed galaxy structure.
Allowing for this, we find that broken structural and
dynamical homology are partly responsible for the `tilt' of the FP,
changing it from
to
.