##### AUTHOR ####
M. Carmen Eliche-Moral

##### TITLE ####
Reconciling a significant assembly of massive early-type galaxies through major mergers at z<~1 with mass-downsizing

##### ABSTRACT ####
Several studies have tried to ascertain whether or not the increase in abundance
of the early-type galaxies  with time is mainly due to major mergers, reaching opposite
conclusions. We have tested it directly through semi-analytical modelling, by studying
how the massive early-type galaxies with log(M_*/Msun)>11 at z~0 (mETGs) would have
evolved backwards-in-time, under the hypothesis that each major merger gives place
to an early-type galaxy. The study was carried out just considering the major mergers
strictly reported by observations at each redshift, and assuming that gas-rich major
mergers experience transitory phases of dust-reddened, star-forming galaxies (DSFs).
The model is able to reproduce the observed evolution of the galaxy LFs at z<~1,
simultaneously for different rest-frame bands and selection criteria on color and
morphology. It also provides a framework in which apparently-contradictory results
on the recent evolution of the luminosity function of massive, red galaxies can be
reconciled, just considering that observational samples of red galaxies can be significantly
contaminated by DSFs. The model proves that it is feasible to build up ~50-60% of
the present-day mETG population at z<~1 through the coordinated action of wet, mixed,
and dry major mergers, fulfilling global trends that are in general agreement with
mass-downsizing. The bulk of this assembly takes place during ~1 Gyr elapsed at 0.8<z<1,
providing a straightforward explanation to the observational fact that redshift z~0.8
is a transition epoch in the recent assembly of mETGs. The gas-rich progenitors of
these recently-assembled mETGs reproduce naturally the excess by a factor of ~4-5
of late-type galaxies observed at 0.8<z<1, as compared to pure luminosity evolution
(PLE) models. The model suggests that major mergers must have been the main driver
for the observational migration of mass from the massive-end of the blue galaxy cloud
to that of the red sequence in the last ~8 Gyr.