The manifold spectra and morphologies of EROs

Deep VLT optical spectroscopy, HST+ ACS (GOODS) imaging and VLA observations are used to unveil the nature of a complete sample of 47 EROs with R- K-s > 5 and K-s < 20. The spectroscopic redshift completeness is 62%. Morphological classification was derived for each ERO through visual inspection and surface brightness profile fitting. Three main ERO morphological types are found: E/S0 galaxies (similar to 30-37%), spiral-like (similar to 24-46%) and irregular systems (similar to 17-39%). The only ERO detected in the radio is likely to host an obscured AGN. The average radio luminosity of the star-forming EROs undetected in the radio implies star formation rates of the order of similar to 33 M-. yr(-1). The colors, redshifts and masses of the E/S0 galaxy subsample imply a minimum formation redshift z(f) similar to 2. With this z(f) there is enough time to have old and massive stellar spheroids already assembled at z similar to 1. We verify that the R - K-s vs. J - K-s color diagram is efficient in segregating old and dusty-star-forming EROs.