Evolutionary paths among different red galaxy types at 0.3 < z < 1.5 and
  the late buildup of massive E-S0's through major mergers
  Some recent observations seem to disagree with hierarchical theories of
galaxy formation about the role played by major mergers in the late buildup of
massive E-S0's. We re-address this question by analysing the morphology,
structural distortion level, and star formation enhancement of a sample of
massive galaxies (M_* > 5 * 10^10 Msun) lying on the Red Sequence and its
surroundings at 0.3 < z < 1.5. We have used an initial sample of ~1800 sources
with K_s < 20.5 mag over an area ~155 arcmin^2 on the Groth Strip, combining
data from the Rainbow Extragalactic Database and the GOYA Survey. Red galaxy
classes that can be directly associated to intermediate stages of major mergers
and to their final products have been defined. We report observational evidence
of the existence of a dominant evolutionary path among massive red galaxies at
0.6<z<1.5, consisting in the conversion of irregular disks into irregular
spheroids, and of these ones into regular spheroids. This result implies that:
1) the massive red regular galaxies at low redshifts derive from the irregular
ones populating the Red Sequence and its neighbourhood at earlier epochs up to
z~1.5; 2) the progenitors of the bulk of present-day massive red regular
galaxies have been blue disks that have migrated to the Red Sequence mostly
through major mergers at 0.6 < z < 1.2 (these mergers thus starting at z~1.5);
and 3) the formation of E-S0's that end up with M_*> 10^11 Msun at z=0 through
gas-rich major mergers has frozen since z~0.6. All these facts support that
major mergers have played the dominant role in the definitive buildup of
present-day E-S0's with M_*> 10^11 Msun at 0.6<z<1.2, in good agreement with
hierarchical scenarios of galaxy formation.
