The VIMOS VLT Deep Survey: the faint type-1 AGN sample
Abstract
We present the type-1 active galactic nuclei (AGN) sample extracted from the VIMOS VLT Deep Survey first observations of 21000 spectra in 1.75 square degree. This sample, which is purely magnitude limited, free of morphological or color selection biases, contains 130 broad line AGN (BLAGN) spectra with redshift up to 5. Our data are divided into a wide (Iab < 22.5) and a deep (Iab < 24) subsample containing 56 and 74 objects respectively. Because of its depth and selection criteria, this sample is uniquely suited to study the population of faint type-1 AGN. Our measured surface density (~ 472 +- 48 BLAGN per square degree with Iab < 24) is significantly higher than that of any other optically selected sample of BLAGN with spectroscopic confirmation. By applying a morphological and color analysis to our AGN sample we find that: (1)~23% of the AGN brighter than Iab=22.5 are classified as extended; this percentage increases to ~42% for those with z < 1.6; (2) a non-negligible fraction of our BLAGN are lying close to the color space area occupied by stars in u*-g' versus g'-r' color-color diagram. This leads us to the conclusion that classical optical ultraviolet preselection technique, if employed at such deep magnitudes (Iab=22.5) in conjuction with a preselection of point-like sources, can miss miss up to ~35% of the AGN population. Finally, we present a composite spectrum of our sample of objects. While the continuum shape is very similar to that of the SDSS composite at short wavelengths, it is much redder than it at lambda > 3000 A. We interpret this as due to significant contamination from emission of the host galaxies, as expected from the faint absolute magnitudes sampled by our survey.
Cite
@article{arxiv.astro-ph/0606060,
title = {The VIMOS VLT Deep Survey: the faint type-1 AGN sample},
author = {I. Gavignaud and A. Bongiorno and S. Paltani and G. Mathez and G. Zamorani and P. Moller and J. P. Picat and V. Le Brun and B. Marano and O. Le Fevre and D. Bottini and B. Garilli and D. Maccagni and R. Scaramella and M. Scodeggio and L. Tresse and G. Vettolani and A. Zanichelli and C. Adami and M. Arnaboldi and S. Arnouts and S. Bardelli and M. Bolzonella and A. Cappi and S. Charlot and P. Ciliegi and T. Contini and S. Foucaud and P. Franzetti and L. Guzzo and O. Ilbert and A. Iovino and H. J. McCracken and C. Marinoni and A. Mazure and B. Meneux and R. Merighi and R. Pello and A. Pollo and L. Pozzetti and M. Radovich and E. Zucca and M. Bondi and G. Busarello and O. Cucciati and S. de la Torre and L. Gregorini and F. Lamareille and Y. Mellier and P. Merluzzi and V. Ripepi and D. Rizzo and D. Vergani},
journal= {arXiv preprint arXiv:astro-ph/0606060},
year = {2007}
}
Comments
Accepted to A&A, 18 pages, 14 figures