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K-band galaxy number counts (GNCs) exhibit a slope change at K~17.5 mag not present in optical bands. To unveil the nature of this feature, we have derived the contribution of different galaxy types to the total K-band GNCs at 0.3<z<1.5 by redshift bins and compared the results with expectations from several galaxy evolutionary models. We show that the slope change is caused by a sudden swap of the galaxy population that numerically dominates the total GNCs (from quiescent E-S0s at K<17.5 mag to blue star-forming discs at fainter magnitudes), and that it is associated with a flattening of the contribution of the E-S0s at 0.6<z<1 to the total GNCs. We confirm previous studies showing that models in which the bulk of massive E-S0s have evolved passively since z>2 cannot predict the slope change, whereas those imposing a relatively late assembly on them (z<1.5) can reproduce it. The K-band GNCs by redshift bins and morphological types point to a progressively definitive build-up of ~50% of this galaxy population at 0.8<z<1.5, which can be explained only through the major mergers reported by observations. We conclude that the slope change in total K-band GNCs is a vestige of the definitive assembly of a substantial fraction of present-day massive E-S0s at 0.8<z<1.5.
We report the likely identification of a substantial population of massive M~10^11M_Sun galaxies at z~4 with suppressed star formation rates (SFRs), selected on rest-frame optical to near-IR colors from the FourStar Galaxy Evolution Survey. The obser
Massive Ultracompact Galaxies (MUGs) are common at z=2-3, but very rare in the nearby Universe. Simulations predict that the few surviving MUGs should reside in galaxy clusters, whose large relative velocities prevent them from merging, thus maintain
[abridged] The mass-size relation of early-type galaxies (ETGs) has been largely studied in the last years to probe the mass assembly of the most massive objects in the Universe. In this paper, we focus on the mass-size relation of quiescent massive
The rest-frame UV-optical (i.e., NUV-B) color index is sensitive to the low-level recent star formation and dust extinction, but it is insensitive to the metallicity. In this Letter, we have measured the rest-frame NUV-B color gradients in ~1400 larg
We study the stellar mass assembly of the Spiderweb Galaxy (MRC 1138-262), a massive z = 2.2 radio galaxy in a protocluster and the probable progenitor of a brightest cluster galaxy. Nearby protocluster galaxies are identified and their properties ar