et al. 2006) in its revised and updated version (Santini et al. 2009). In particular the new cataloger contains 24 micron data from Spitzer/MIPS observations and a revised and more accurate IRAC photometry. New spectra from public surveys (Vanzella et al. 2009; Popesso et al. 2009) were also added. We also include an analysis of the deep X-ray data available for the field i.e. the 2 Ms Chandra exposure (Luo et al. 2008) that allows us to study the star formation and/or AGN content in an independent way.\
All magnitudes are in the AB system (except where otherwise stated) and we adopt the $\Lambda$-CDM concordance cosmological model ($H_0=70$, $\Omega_M=0.3$ and $\Omega_{\Lambda}=0.7$).

The sample 
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To select z$\sim 3 $ galaxies we have adapted the usual Lyman break technique to the filters adopted in the GOODS survey, which is different from the classical UGR set used by Steidel et al. 2003 (see also Giavalisco et al. 2004). The redshift $\sim 3$ objects are selected as U–dropouts according to the following cuts:

$$\displaystyle -0.2 \le V-I \le 0.35$$ $$\displaystyle U-V \ge 0.75(V-I)+1.15$$ which are effective at $2.4\le z\le 3.5$. These cuts were determined by Grazian et al. (2007) using our multicolor GOODS-MUSIC 