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Chandra Deep Field South AGN Spectral Properties Catalog

Published by High Energy Astrophysics Science Archive Research Center | National Aeronautics and Space Administration | Metadata Last Checked: February 14, 2026 | Last Modified: 2026-02-10
This table contains the results of a detailed X-ray spectral analysis of the sources in the 1 Ms catalog of the Chandra Deep Field South (CDFS, Giacconi et al. 2002, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/139/369">CDS Cat. J/ApJS/139/369</a>, available in Browse as the CHANDFS1MS table), taking advantage of optical spectroscopy and photometric redshifts for 321 extragalactic sources out of the total sample of 347 sources. As a default spectral model, the authors adopt a power law with a slope Gamma with an intrinsic redshifted absorption N<sub>H</sub>, a fixed Galactic absorption and an unresolved Fe emission line. For 82 X-ray bright sources, they are able to perform the X-ray spectral analysis leaving both Gamma and N<sub>H</sub> free. The weighted mean value for the slope of the power law is 1.75 +/- 0.02, and the distribution of best fit values shows an intrinsic dispersion of 0.30. The authors do not find hints of a correlation between the spectral index Gamma and the intrinsic absorption column density N<sub>H</sub>. They then investigate the absorption distribution for the whole sample, deriving the N<sub>H</sub> values in faint sources by fixing Gamma to be 1.8. The authors find that the fraction of absorbed sources (with N<sub>H</sub> > 10<sup>22</sup> cm<sup>-2</sup>) in the sample is constant (at the level of about 75%) or moderately increasing with redshift. Finally, they compare the optical classification to the X-ray spectral properties, confirming that the correspondence of unabsorbed (absorbed) X-ray sources to optical type I (type II) AGN is accurate for at least 80% of the sources with spectral identification (1/3 of the total X-ray sample). This table was created by the HEASARC in August 2007 primarily based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/451/457">CDS Catalog J/A+A/451/457</a> file table1.dat. The positions of the X-ray sources were taken from <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/139/369">CDS Catalog J/ApJS/139/369</a> (Giacconi et al. 2002), except for that of source number 901 which was taken from Table 5 of Szokoly et al. (2004, ApJS, 155, 271). This is a service provided by NASA HEASARC .

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