TY - JOUR
T1 - The Extended Chandra Deep Field-South survey
T2 - Optical spectroscopy of faint X-ray sources with the VLT* and Keck
AU - Silverman, J. D.
AU - Mainieri, V.
AU - Salvato, M.
AU - Hasinger, G.
AU - Bergeron, J.
AU - Capak, P.
AU - Szokoly, G.
AU - Finoguenov, A.
AU - Gilli, R.
AU - Rosati, P.
AU - Tozzi, P.
AU - Vignali, C.
AU - Alexander, D. M.
AU - Brandt, W. N.
AU - Lehmer, B. D.
AU - Luo, B.
AU - Rafferty, D.
AU - Xue, Y. Q.
AU - Balestra, I.
AU - Bauer, F. E.
AU - Brusa, M.
AU - Comastri, A.
AU - Kartaltepe, J.
AU - Koekemoer, A. M.
AU - Miyaji, T.
AU - Schneider, D. P.
AU - Treister, E.
AU - Wisotski, L.
AU - Schramm, M.
PY - 2010/11
Y1 - 2010/11
N2 - We present 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 our new spectroscopic identifications are mainly associated with X-ray sources in the shallower 250 ks coverage, we 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. We demonstrate the remarkable coverage of the luminosity-redshift plane now accessible from our data while emphasizing the detection of active galactic nuclei (AGNs) that contribute to the faint end of the luminosity function (L0.5-8 keV ∼ 1043-1044 erg s-1) at 1.5 ≤ z ≤ 3 including those with and without broad emission lines. Our redshift catalog includes 17 type-2 QSOs at 1 ≤ z ≤ 3.5 that significantly increases such samples (2×). Based on our deepest (9 hr) VLT/VIMOS observation, we identify "elusive" optically faint galaxies (Rmag ∼ 25) at z ∼ 2-3 based upon the detection of interstellar absorption lines (e.g., Oii+Siiv, Cii], Civ); we 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, we determine accurate distances to eight galaxy groups with extended X-ray emission detected both by Chandra and XMM-Newton. Finally, we measure the physical extent of known large-scale structures (z ∼ 0.7) evident in the CDF-S. While a thick sheet (a radial size of 67.7 Mpc) at z ∼ 0.67 extends over the full field, the z ∼ 0.73 structure is thin (18.8 Mpc) and filamentary as traced by both AGNs and galaxy groups. In the Appendix, we provide spectroscopic redshifts for 49 counterparts to fainter X-ray sources detected only in the 1 and 2 Ms catalogs, and 48 Very Large Array radio sources not detected in X-rays.
AB - We present 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 our new spectroscopic identifications are mainly associated with X-ray sources in the shallower 250 ks coverage, we 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. We demonstrate the remarkable coverage of the luminosity-redshift plane now accessible from our data while emphasizing the detection of active galactic nuclei (AGNs) that contribute to the faint end of the luminosity function (L0.5-8 keV ∼ 1043-1044 erg s-1) at 1.5 ≤ z ≤ 3 including those with and without broad emission lines. Our redshift catalog includes 17 type-2 QSOs at 1 ≤ z ≤ 3.5 that significantly increases such samples (2×). Based on our deepest (9 hr) VLT/VIMOS observation, we identify "elusive" optically faint galaxies (Rmag ∼ 25) at z ∼ 2-3 based upon the detection of interstellar absorption lines (e.g., Oii+Siiv, Cii], Civ); we 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, we determine accurate distances to eight galaxy groups with extended X-ray emission detected both by Chandra and XMM-Newton. Finally, we measure the physical extent of known large-scale structures (z ∼ 0.7) evident in the CDF-S. While a thick sheet (a radial size of 67.7 Mpc) at z ∼ 0.67 extends over the full field, the z ∼ 0.73 structure is thin (18.8 Mpc) and filamentary as traced by both AGNs and galaxy groups. In the Appendix, we provide spectroscopic redshifts for 49 counterparts to fainter X-ray sources detected only in the 1 and 2 Ms catalogs, and 48 Very Large Array radio sources not detected in X-rays.
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U2 - 10.1088/0067-0049/191/1/124
DO - 10.1088/0067-0049/191/1/124
M3 - Article
AN - SCOPUS:78650196581
SN - 0067-0049
VL - 191
SP - 124
EP - 142
JO - Astrophysical Journal, Supplement Series
JF - Astrophysical Journal, Supplement Series
IS - 1
ER -