The Chandra Deep Field-South: Optical Spectroscopy. I.
The Chandra Deep Field-South: Optical Spectroscopy. I.
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DOI：
10.1086/424707
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发表时间：
2003-12
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通讯作者：
G. Szokoly;J. Bergeron;G. Hasinger;I. Lehmann;L. Kewley;L. Kewley;V. Mainieri;M. Nonino;P. Rosati;R. Giacconi;R. Gilli;R. Gilmozzi;C. Norman;M. Romaniello;E. Schreier;E. Schreier;P. Tozzi;Jing Wang;W. Zheng;A. Zirm
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文献类型：
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作者：
G. Szokoly;J. Bergeron;G. Hasinger;I. Lehmann;L. Kewley;L. Kewley;V. Mainieri;M. Nonino;P. Rosati;R. Giacconi;R. Gilli;R. Gilmozzi;C. Norman;M. Romaniello;E. Schreier;E. Schreier;P. Tozzi;Jing Wang;W. Zheng;A. Zirm
本文介绍了钱德拉深场南（CDFS） 942 k曝光中探测到的x射线源的光谱跟踪程序的结果。在VLT上，用FORS1/FORS2光谱仪对349个钱德拉源中的251个（包括三个额外的微弱x射线源）进行了总共288个可能的对应观测。给出了所有观测源的光谱和R波段图像，并给出了大多数源的R- K色。168个x射线源获得了光谱红移，其中137个既有可靠的光学识别又有可靠的红移估计（包括16个外部识别）。zb> 2的r1044 ergs s-1（13个具有明确光谱识别的源）；大多数x射线1型qso是明亮的，R > 24，而大多数x射线2型qso的R > 24，这可以解释与CDFN结果的差异，因为r> 24 CDFN x射线对应体很少获得光谱红移。在z ~ 0.5处存在x射线1型qso，但在z 5处明显减少，其分数随光通量的减小而明显增加，在R≥24的样品中最高可达25%。它们覆盖了x射线硬度比的整个范围，包括各种类型的物体（特别是z≥1 x射线吸收agn的很大一部分，但也包括椭圆星系和星爆星系），其中一半以上应该是相当明亮的x射线源[LX(0.5-10 keV) > 1042 ergs -1]。光度红移是导出x射线选择的EROs的性质和演化所必需的。
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). A total of 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 colors 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 1044 ergs s-1] at z > 2 (13 sources with unambiguous spectroscopic identification); most X-ray type 1 QSOs are bright, R ≲ 24, whereas most X-ray type 2 QSOs have R ≳ 24, which may explain the difference with the CDFN results as few spectroscopic redshifts were obtained for R > 24 CDFN X-ray counterparts. There are X-ray type 1 QSOs down to z ~ 0.5, but a strong decrease at z 5) as X-ray counterparts, and their fraction strongly increases with decreasing optical flux, up to 25% for the R ≥ 24 sample. They cover the whole range of X-ray hardness ratios, comprise objects of various classes (in particular a high fraction of z ≳ 1 X-ray absorbed AGNs, but also elliptical and starburst galaxies) and more than half of them should be fairly bright X-ray sources [LX(0.5-10 keV) > 1042 ergs s-1]. Photometric redshifts will be necessary to derive the properties and evolution of the X-ray selected EROs.