The manifold spectra and morphologies of EROs
Abstract
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-Ks>5 and Ks<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 (30-37%), spiral-like (24-46%) and irregular systems (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 33 Msun yr^-1. The colors, redshifts and masses of the E/S0 galaxy subsample imply a minimum formation redshift z_f \sim 2. With this z_f there is enough time to have old and massive stellar spheroids already assembled at z \sim 1. We verify that the R-Ks vs. J-Ks color diagram is efficient in segregating old and dusty-star-forming EROs.
Cite
@article{arxiv.astro-ph/0310742,
title = {The manifold spectra and morphologies of EROs},
author = {A. Cimatti and E. Daddi and P. Cassata and E. Pignatelli and G. Fasano and J. Vernet and E. Fomalont and K. Kellermann and G. Zamorani and M. Mignoli and L. Pozzetti and A. Renzini and S. di Serego Alighieri and A. Franceschini and E. Giallongo and A. Fontana},
journal= {arXiv preprint arXiv:astro-ph/0310742},
year = {2009}
}
Comments
5 pages, 5 figures, to appear in Astronomy & Astrophysics Letters