SIMBAD references

Using the UltraVISTA catalogs, we investigate the evolution in the 11.4 Gyr since z = 3 of the progenitors of local ultra-massive galaxies (log (M_star/M_☉) ~ 11.8; UMGs), providing a complete and consistent picture of how the most massive galaxies at z = 0 have assembled. By selecting the progenitors with a semi-empirical approach using abundance matching, we infer a growth in stellar mass of 0.56_–0.25^+0.35 dex, 0.45_–0.20^+0.16 dex, and 0.27_–0.12^+0.08 dex from z = 3, z = 2, and z = 1, respectively, to z = 0. At z < 1, the progenitors of UMGs constitute a homogeneous population of only quiescent galaxies with old stellar populations. At z > 1, the contribution from star-forming galaxies progressively increases, with the progenitors at 2 < z < 3 being dominated by massive (M_star~ 2x10¹¹ M_☉), dusty (A_V∼ 1-2.2 mag), star-forming (SFR ∼ 100-400 M_☉/yr) galaxies with a large range in stellar ages. At z = 2.75, ∼15% of the progenitors are quiescent, with properties typical of post-starburst galaxies with little dust extinction and strong Balmer break, and showing a large scatter in color. Our findings indicate that at least half of the stellar content of local UMGs was assembled at z > 1, whereas the remaining was assembled via merging from z ∼ 1 to the present. Most of the quenching of the star-forming progenitors happened between z = 2.75 and z = 1.25, in good agreement with the typical formation redshift and scatter in age of z = 0 UMGs as derived from their fossil records. The progenitors of local UMGs, including the star-forming ones, never lived on the blue cloud since z = 3. We propose an alternative path for the formation of local UMGs that refines previously proposed pictures and that is fully consistent with our findings.