Volume 412, Number 1, December II 2003
|Page(s)||L1 - L5|
|Published online||25 November 2003|
Letter to the Editor
The manifold spectra and morphologies of EROs*
INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
2 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
3 Dipartimento di Astronomia, Università di Padova, Vicolo dell'Osservatorio, 2, 35122 Padova, Italy
4 INAF – Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio, 5, 35122 Padova, Italy
5 National Radio Astronomy Observatory, Charlottesville, VA 22903, USA
6 INAF – Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
7 INAF – Osservatorio Astronomico di Roma, via dell'Osservatorio 2, Monteporzio, Italy
Corresponding author: A. Cimatti, firstname.lastname@example.org
Accepted: 13 October 2003
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 and . 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 (∼%), spiral-like (~%) and irregular systems (~%). 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 ~33 yr-1. The colors, redshifts and masses of the E/S0 galaxy subsample imply a minimum formation redshift . With this zf there is enough time to have old and massive stellar spheroids already assembled at . We verify that the vs. color diagram is efficient in segregating old and dusty-star-forming EROs.
Key words: galaxies: evolution / galaxies: elliptical and lenticular, cD / galaxies: starbust / galaxies: formation
© ESO, 2003
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