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CDFSAGNCXO - Chandra Deep Field South AGN Spectral Properties Catalog

HEASARC
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Overview

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, CDS Cat. J/ApJS/139/369, 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_H, 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_H 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_H. They then investigate the absorption distribution for the whole sample, deriving the N_H values in faint sources by fixing Gamma to be 1.8. The authors find that the fraction of absorbed sources (with N_H > 10^22 cm^-2) 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).

Catalog Bibcodes

2006A&A...451..457T
2002ApJS..139..369G

References

X-ray spectral properties of active galactic nuclei in the
Chandra Deep Field South.
    Tozzi P., Gilli R., Mainieri V., Norman C., Risaliti G., Rosati P.,
    Bergeron J., Borgani S., Giacconi R., Hasinger G., Nonino M.,
    Streblyanska A., Szokoly G., Wang J.X., Zheng W.
   <Astron. Astrophys., 451, 457-474 (2006)>
   =2006A&A...451..457T
Chandra Deep Field South: the 1 Ms catalog.
   Giacconi R., Zirm A., Wang J., Rosati P., Nonino M., Tozzi P., Gilli R.,
   Mainieri V., Hasinger G., Kewley L., Bergeron J., Borgani S., Gilmozzi R.,
   Grogin N., Koekemoer A., Schreier E., Zheng W., Norman C.
   <Astrophys. J. Suppl. Ser. 139, 369 (2002)>
   =2002ApJS..139..369G

Provenance

This table was created by the HEASARC in August 2007 primarily based on CDS Catalog J/A+A/451/457 file table1.dat. The positions of the X-ray sources were taken from CDS Catalog J/ApJS/139/369 (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).

Parameters

Source_Number
A unique X-ray detection identification running number (XID), first used by Giacconi et al. (2002) to identify 346 sources in the CDFS, and with 3 sources (901, 902 and 903) subsequently added by Szokoly et al. (2004, ApJS, 155, 271).

Name
The name of the X-ray source using the naming convention recommended by the CDS Dictionary of Nomenclature of Celestial Objects '[GZW2002] XID NNN', in which GZW2002 refers to the original CDFS reference (Giacconi, Zirm, Wang 2002), and NNN is the X-ray source number.

RA
The Right Ascension of the Chandra X-ray source, in the selected equinox, taken from CDS Catalog J/ApJS/139/369 (Giacconi et al. 2002), except for the position of source number 901 which was taken from Table 5 of Szokoly et al. (2004, ApJS, 155, 271). #

Dec
The Declination of the Chandra X-ray source, in the selected equinox, taken from CDS Catalog J/ApJS/139/369 (Giacconi et al. 2002), except for the position of source number 901 which was taken from Table 5 of Szokoly et al. (2004, ApJS, 155, 271).

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Redshift
The redshift of the optical/near-infcrared counterpart to the X-ray source.

Redshift_Flag
This parameter (Q) contains information on the source of the redhift information, as follows: quality flags with Q >= 1 indicate optical spectral quality while Q < 1 indicate the reshift was obtained photometrically. For spectroscopic redshifts:

        Q = 1 corresponds to spectra with a single optical line identified
        Q = 2 indicates secure spectra but uncertain counterpart
        Q = 3 indicates a secure redshift
  
The photometric redshifts were obtained from different methods as described in Zheng et al. (2004, ApJS, 155, 73): HyperZ (Q = 0.2), BPZ (Q = 0.3), COMBO-17 (Q = 0.4). When there are consistent redshifts from more than one method, the corresponding quality flag is the sum of the individual Q values.

Spectral_Index
The spectral slope Gamma in the 0.5 - 7 keV band, either as obtained from the spectral fitting or, for the weaker sources, as adopted a priori (in the latter case a fixed value of 1.80 was assumed).

Spectral_Index_Neg_Err
The one-sigma negative error in Gamma (not given for those sources for which a fixed value of 1.80 was assumed).

Spectral_Index_Pos_Err
The one-sigma positive error in Gamma (not given for those sources for which a fixed value of 1.80 was assumed).

NH
The intrinsic absorption H column density N_H, in H atoms cm^-2, as obtained from the spectral fitting or, for the Compton-thick sources, as fixed at 1.50 x 10^24 atoms cm^-2. A fixed Galactic column density of 8 x 10^19 atoms cm^-2 in this direction was also assumed.

NH_Neg_Err
The one-sigma negative error in N_H, in H atoms cm^-2 (not given for those sources for which a fixed value of 1.50 a 10^24 atoms cm^-2 was assumed).

NH_Pos_Err
The one-sigma positive error in N_H, in H atoms cm^-2 (not given for those sources for which a fixed value of 1.50 a 10^24 atoms cm^-2 was assumed).

SB_Lx
The soft-band (0.5 - 2 keV) luminosity of the source, in erg/s, computed for a flat Lambda cosmology and a Hubble constant H_0 of 70 km s^-1 Mpc^-1.

HB_Lx
The hard-band (2 - 10 keV) luminosity of the source, in erg/s, computed for a flat Lambda cosmology and a Hubble constant H_0 of 70 km s^-1 Mpc^-1.

SB_Flux
The soft-band (0.5 - 2 keV) flux of the X-ray source, in erg/s/cm^2.

HB_Flux
The hard-band (2 - 10 keV) flux of the X-ray source, in erg/s/cm^2.

Xtype
The X-Type parameter indicating the type of best-fit spectral model used, coded as follows:

       C-thick = sources for which the best fit is given by a PEXRAV model
                 (exponentially cut-off power law plus a reflection component
                 from neutral material, Magdziarz & Zdziardski,
                 1995MNRAS.273..837M)
       C-thin  = sources for which the best fit model is a power law with
                 intrinsic absorption
       Soft-C  = sources whose best fit model includes a soft component with
                 the same slope of the main power law.
  

Contact Person

Questions regarding the CDFSAGNCXO database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 1-Aug-2007