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arXiv · astro-ph/0312324

The Chandra Deep Field South: Optical Spectroscopy I

G. P. Szokoly·J. Bergeron·G. Hasinger·I. Lehmann·L. Kewley·V. Mainieri·M. Nonino·P. Rosati·R. Giacconi·R. Gilli·R. Gilmozzi·C. Norman·M. Romaniello·E. Schreier·P. Tozzi·J. X. Wang·W. Zheng·A. Zirm
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Abstract

We present the results of our spectroscopic follow-up program of the X-ray sources detected in the 942 ks exposure of the Chandra Deep Field South (CDFS). 288 possible counterparts were observed at the VLT with the FORS1/FORS2 spectrographs for 251 of the 349 Chandra sources (including three additional faint X-ray sources). Spectra and R-band images are shown for all the observed sources and R-K colours are given for most of them. Spectroscopic redshifts were obtained for 168 X-ray sources, of which 137 have both reliable optical identification and redshift estimate (including 16 external identifications). The R<24 observed sample comprises 161 X-ray objects (181 optical counterparts) and 126 of them have unambiguous spectroscopic identification. We introduce a new classification based solely on X-ray properties, HR and X-ray luminosity, consistent with the unified AGN model. This X-ray classification uncovers a large fraction of optically obscured, X-ray luminous AGNs missed by the classical optical classification.

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G. P. Szokoly, J. Bergeron, G. Hasinger, I. Lehmann, L. Kewley, V. Mainieri, M. Nonino, P. Rosati, R. Giacconi, R. Gilli, R. Gilmozzi, C. Norman, M. Romaniello, E. Schreier, P. Tozzi, J. X. Wang, W. Zheng, A. Zirm. 2004-07-07. The Chandra Deep Field South: Optical Spectroscopy I. https://doi.org/10.1086/424707

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