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Description
This table contains the results of a program to acquire high-quality optical spectra of X-ray sources detected in the Extended-Chandra Deep Field-South (E-CDF-S) and its central 2 Ms area. New spectroscopic redshifts, up to z = 4, are measured for 283 counterparts to Chandra sources with deep exposures (t ~ 2-9 hr per pointing) using multi-slit facilities on both VLT (VIMOS) and Keck (DEIMOS), thus bringing the total number of spectroscopically identified X-ray sources to over 500 in this survey field. Since their new spectroscopic identifications are mainly associated with X-ray sources in the shallower 250 ks coverage, the authors provide a comprehensive catalog of X-ray sources detected in the E-CDF-S including the optical and near-infrared counterparts, determined by a likelihood routine, and redshifts (both spectroscopic and photometric), that incorporate published spectroscopic catalogs, thus resulting in a final sample with a high fraction (80%) of X-ray sources having secure identifications. The authors demonstrate the remarkable coverage of the luminosity-redshift plane now accessible from their data while emphasizing the detection of active galactic nuclei (AGNs) that contribute to the faint end of the luminosity function (L<sub>0.5-8keV</sub> ~ 10<sup>43</sup> - 10<sup>44</sup> erg s<sup>-1</sup>) at 1.5 <~ z <~ 3, including those with and without broad emission lines. This redshift catalog includes 17 type-2 QSOs at 1 <~ z <~ 3.5 that significantly increases (doubles) such samples. Based on thei deepest (9 hr) VLT/VIMOS observation, the authors identify "elusive" optically faint galaxies (R<sub>mag</sub> ~ 25) at z ~ 2 - 3 based upon the detection of interstellar absorption lines (e.g., O II+Si IV, C II], C IV); in their paper, they highlight one such case, an absorption-line galaxy at z = 3.208 having no obvious signs of an AGN in its optical spectrum. In addition, they determine accurate distances to eight galaxy groups with extended X-ray emission detected both by Chandra and XMM-Newton. This online catalog was created by the HEASARC in November 2010 based on a machine-readable version of Table 4 from the paper which was obtained from the ApJ website. This is a service provided by NASA HEASARC .
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