Key points are not available for this paper at this time.
Spectroscopic redshifts have been measured for nine K-band luminous galaxies at 1.7<z<2.3, selected with K-s<20 in the K20 survey region of the Great Observatories Origins Deep Survey (GOODS) area. Star formation rates (SFRs) of 100-500 M- yr(-1) are derived when dust extinction is taken into account. The fitting of their multicolor spectral energy distributions indicates stellar masses of M10(11) M- for most of the galaxies. Their rest-frame UV morphology is highly irregular, suggesting that merging-driven starbursts are going on in these galaxies. Morphologies tend to be more compact in the near-IR, a hint for the possible presence of older stellar populations. Such galaxies are strongly clustered, with seven out of nine belonging to redshift spikes, which indicates a correlation length of r(0)9-17 h(-1) Mpc (1 ς range). Current semianalytical models of galaxy formation appear to underpredict by a large factor (30) the number density of such a population of massive and powerful starburst galaxies at z2. The high masses and SFRs, together with the strong clustering, suggest that at z2 we may have started to explore the major formation epoch of massive early-type galaxies.
Daddi et al. (Fri,) studied this question.