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We present results from a study to determine how star formation contributes to galaxy growth since redshift z = 1.5. Using galaxies from the MUnich Near-Infrared Cluster Survey (MUNICS) and the FORS Deep Field (FDF), we investigate the specific star formation rate (SSFR, star formation rate [SFR] per unit galaxy stellar mass) as a function of galaxy stellar mass and redshift. We test the compatibility of our results with a sample drawn from a larger volume using the Sloan Digital Sky Survey. We find that the SSFR decreases as galaxy stellar mass increases, suggesting that star formation contributes more to the growth of low-mass galaxies than high-mass galaxies at all redshifts in this study. [ABSTRACT FROM AUTHOR]

Deep multicolor fields are an important tool to explore the formation and evolution of galaxies out to the highest redshifts and faintest magnitude limits (Ferguson et al. [11]). This is also the aim of the FORS Deep Field (FDF), which has about 5 times the field-size of the two Hubble Deep Fields together and, in addition, contains a relatively bright quasar of 18.5mag at z = 3.36 at its center. A full exploration of the FDF multicolor data requires good photometric redshifts. In this paper we provide an overview of the data, describe our photometric redshift technique and present the redshift distribution in the FDF. [ABSTRACT FROM AUTHOR]

X-ray selected EROs are, on average, the hardest X-ray sources in medium and deep X-ray fields. This coupled with their extremely red colors (R-K > 5) suggest that they represent one of the most promising population where looking for high-luminosity (LX > 1044 erg s-1) and X-ray obscured (NH > 1022 cm-2) type2 AGNs, the so called QSO2 (e.g., [5]; [4]; Mignoli et al. submitted to A&A). These latter are predicted in large density by the synthesis model of the Cosmic X-ray background [9] even if only few observational evidences have been found so far (e.g., [1] and references therein; Caccianiga et al. A&A accepted). [ABSTRACT FROM AUTHOR]

How and when present-day massive early-type galaxies built up and what type of evolution has characterized their growth (star formation and/or merging) still remain open issues. The different competing scenarios of galaxy formation predict much different properties of early-type galaxies at z > 1. The "monolithic" collapse predicts that massive spheroids formed at high redshift (z > 2.5-3) and that their comoving density is constant at z < 2.5-3 since they evolve only in luminosity. On the contrary, in the hierarchical scenario massive spheroids are built up through subsequent mergers reaching their final masses at z < 1.5 [3,5]. As a consequence, massive systems are very rare at z > 1, their comoving density decreases from z = 0 to z ~ 1.5 and they should experience their last burst of star formation at z < 1.5, concurrent with the merging event(s) of their formation. These opposed predicted properties of early-types at z > 1 can be probed observationally once a well defined sample of massive early-types at z > 1 is available. We are constructing such a sample through a dedicated near-IR very low resolution (λ/Δλ≃50) spectroscopic survey (TNG EROs Spectroscopic Identification Survey, TESIS, [6]) of a complete sample of 30 bright (K < 18.5) Extremely Red Objects (EROs). [ABSTRACT FROM AUTHOR]