SIMBAD references

The influence of a dark component on the first epoch of galaxy formation is analyzed by using the ages of the three oldest high-redshift galaxies known in the literature. Our results, based on a spatially flat accelerated universe driven by a ``quintessence'' component (p_x=ωρ_x), show that, if the inferred ages of these objects are correct, the first formation era is pushed back to extremely high redshifts. For the present best-fit quintessence model (Ω_x=0.7, ω←0.6), we find a lower bound of z_f≥7.7, whereas in the extreme case of the Λ+cold dark matter model (ω=-1) the limit is slightly smaller (z_f≥5.8). The case for open cold dark matter models has also been discussed. For Ω_m≃0.3, the formation redshift is restricted by z_f≥18. As a general result, if Ω_m≥0.37, these galaxies are not formed in FRW cosmologies with no dark energy since for all these cases z_f⟶∞.