The role of the LIRG and ULIRG phases in the evolution of Ks-selected galaxies

Aims.We investigate the role of the luminous infrared galaxy (LIRG) and ultra-luminous infrared galaxy (ULIRG) phases in the evolution of K_s-selected galaxies and, in particular, Extremely Red Galaxies (ERGs).
Methods: .With this aim, we compare the properties of a sample of 2905 K_s<21.5 (Vega mag) galaxies in the GOODS/CDFS with the sub-sample of those 696 sources which are detected at 24 μ m.
Results: .We find that LIRGs constitute 30% of the galaxies with stellar mass M>1×10¹¹ M_⊙ assembled at redshift z=0.5. A minimum of 65% of the galaxies with M>2.5×10¹¹ M_⊙ at z ≈ 2{-}3 are ULIRGs at those redshifts. 60% of the ULIRGs in our sample have the characteristic colours of ERGs. Conversely, 40% of the ERGs with stellar mass M>1.3 ×10¹¹ M_⊙ at 1.5<z<2.0 and a minimum of 52% of those with the same mass cut at 2.0<z<3.0 are ULIRGs. The average optical/near-IR properties of the massive ERGs at similar redshifts that are identified with ULIRGs and that are not have basically no difference, suggesting that both populations contain the same kind of objects in different phases of their lives.
Conclusions: .LIRGs and ULIRGs have an important role in galaxy evolution and mass assembly, and, although they are only able to trace a fraction of the massive (M>1×10¹¹ M_⊙) galaxies present in the Universe at a given time, this fraction becomes very significant (⪆ 50%) at redshifts z ⪆ 2.