Search

The high-z progenitors of local massive early-type galaxies should be characterized by a strong level of clustering, larger than that measured for z=3 Lyman Break Galaxies and comparable to that of z~ 1 EROs. First possible evidences for such strongly clustered objects at $z\gtrsim 2$ were found by the FIRES and K20 surveys, that have identified new classes of faint high-z K-selected galaxies. Some details are given here for the new population of massive star-forming galaxies at z~ 2, found by the K20 survey in the GOODS-South area. Because of their much redder UV continuum, most of these galaxies would not be selected by the Lyman Break criterion. Such objects are good candidates for the precursors of local ellipticals caught in their formation phase. We have calibrated a two color criterion to allow the identification of these highest redshift galaxies in bright K-limited samples. [ABSTRACT FROM AUTHOR]

We present very deep near-infrared imaging in the Js, H and Ks-bands of the HDF-S and the field around the z=0.83 cluster MS1054-03 with ISAAC on the VLT. For the HDF-S this resulted in the deepest ground-based infrared observations to date and the deepest Ks-band in any field. We constructed Ks-selected multicolor catalogs in both fields, selecting high-redshift galaxies on their rest-frame optical light. We discovered a new, substantial population of optically faint galaxies with very red near-infrared colors (Js - Ks > 2.3) which are underrepresented in standard U-dropout samples. Recently, these galaxies were spectroscopically confirmed at redshifts z>2 and we estimate that they may contribute as much as 50% to the total stellar mass density at z~3. Furthermore, the near-infrared data allow direct measurement of the evolution of the global rest-frame optical color, luminosity density, and stellar mass density from z=0 to z=3. We find that the average rest-frame optical color was monotonically bluer in the past and the universe had a ~10 times lower stellar mass density in bright galaxies at z~3. In general, our results demonstrate the necessity of deep near-infrared imaging for a more complete picture of the early universe. [ABSTRACT FROM AUTHOR]

The clustering properties of clusters, galaxies and AGN as a function of redshift are briefly discussed. It appears that extremely red objects at z~ 1, and objects with J-K > 1.7 and photometric redshifts 2 < zphot < 4 are highly clustered, indicating that a majority of these objects are the progenitors of nearby ellipticals. Similarly clustered seem luminous radio galaxies at z~ 1, indicating that these objects comprise a short lived phase in the lifetime of these red objects. The high level of clustering furthermore suggests that distant powerful radio galaxies (e.g. z>2) might be residing in the progenitors of nearby clusters - proto-clusters. A number of observational projects targetting fields with distant radio galaxies, including studies of Lyα and Hα emitters, Lyman break galaxies and (sub)mm and X-ray emitters, all confirm that such radio galaxies are indeed located in proto-clusters. Estimates of the total mass of the proto-clusters are similar to the masses of local clusters. If the total star formation rate which we estimate for the entire proto-clusters is sustained up to z~ 1, the metals in the hot cluster gas of local clusters can easily be accounted for. [ABSTRACT FROM AUTHOR]

We are carrying out a search for Lyα emitting galaxies at z = 6.5 employing slitless spectroscopy at the VLT. In our 43 arcmin2 field we find three isolated single emission lines with SEDs consistent with line emitting galaxies at z = 6.5. [ABSTRACT FROM AUTHOR]