Evolution of the Fundamental Plane for early-type galaxies up to z = 1.2

We studied the evolution of the Fundamental Plane in B- and g-bands, for
two samples of early-type galaxies at 0.2 < z < 0.35 and 0.35 <
z < 1.2. We found a difference in the intercept that can be
interpreted as galaxies at < z > ~0.7 being 0.68 and 0.52 mag
brighter in the B- and g-band respectively, than their local
counterparts. From the study of the Kormendy relation, we found the
existence of a population of very bright (-21.5 > M <SUB>g</SUB> >
-22.5) and compact (Re < 2 kpc) galaxies of which only a small
fraction of 0.4% exists at z = 0, and that would be responsible for the
apparent evolution in the Kormendy relation (Fernández Lorenzo et
al. 2011). These compact objects would have evolved mainly in size by
the action of ``dry’’ minor mergers.

We checked the effect of these bright and compact objects in the FP by
comparing the galaxies with -21.5 > M <SUB>g</SUB> > -22.5 of our
high-redshift sample and the SDSS early-type galaxies of Bernardi et al.
(2003) in Fig. 1. The previous evolution found in the FP seems to be
caused mainly by these galaxies, which have virtually disappeared at z =