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AGNSDSSXMM - SDSS/XMM-Newton AGN Spectral Properties Catalog

HEASARC
Archive

Overview

Bright XMM-Newton data are combined with the Chandra Deep Field South observations to explore the behavior of the intrinsic AGN absorption, as a function of redshift and luminosity. The sample consists of 359 sources selected in the hard 2 - 8 keV band, spanning the flux range from 6 x 10-16 - 3 x 10-13 erg/cm2/s with a high rate of spectroscopic or photometric redshift completeness (100 and 85 per cent for the Chandra and XMM-Newton data, respectively). The authors derive the column density values using X-ray spectral fits. They find that the fraction of obscured AGN falls with increasing luminosity in agreement with previous findings. The fraction of obscured AGN shows an apparent increase at high redshifts (z > 2). Simulations show that this effect can most probably be attributed to the fact that at high redshifts the column densities are overestimated.

This table contains the subset of 153 brighter hard X-ray sources in the XMM-Newton/Sloan Digital Sky Survey (SDSS) sample which have 2-8 keV fluxes > 3 x 10-14 erg cm-2 s-1, excluding a number of sources with extended optical morphology and blue colors, as well as 4 sources with X-ray to optical fluxes < 0.1 which are fit better with stellar rather than QSO templates.

Much more information on the SDSS is available at the project's web site at http://www.sdss.org/.


Catalog Bibcode

2006A&A...459..693A

References

XMM-Newton and Chandra measurements of the AGN intrinsic absorption:
dependence on luminosity and redshift.
    Akylas A., Georgantopoulos I., Georgakakis A., Kitsionas S.,
    Hatziminaoglou E.
   <Astron. Astrophys., 459, 693-701 (2006)>
   =2006A&A...459..693A

Provenance

This table was created by the HEASARC in July 2007 based on CDS Catalog J/A+A/459/693 file table2.dat.

Parameters

Source_Number
A running X-ray source number in order of increasing J2000.0 Right Ascension.

Name
The preferred designation for the X-ray source using the '[AGG2006]' prefix (for Akylas, Georgantopoulos, Georgakakis, 2006) and the source number, as recommended by the CDS Dictionary of Nomenclature of Celestial Objects.

RA
The Right Ascension of the X-ray source in the selected equinox. This was given in J2000.0 coordinates in decimal degrees to a precision of 0.001 degrees (3.6") in the original table.

Dec
The Declination of the X-ray source in the selected equinox. This was given in J2000.0 coordinates in decimal degrees to a precision of 0.001 degrees (3.6") in the original table.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Spectral_Index
The X-ray power-law photon index, Gamma. For sources with adequate count statistics (net source counts >100), the authors used the Chi-squared statistic technique. The data were grouped to give a minimum of 15 counts per bin to ensure that Gaussian statistics apply. The authors adopted an absorbed power-law model and attempted to constrain the intrinsic absorption column density n_H (i.e., having subtracted the Galactic absorption) and Gamma. For the sources with limited photon statistics (net counts <100), they used the C-statistic technique specifically developed to extract spectral information from data with a low signal-to-noise ratio. In this case, the data were grouped to give a minimum of 1 count per bin to avoid zero count bins. The authors tried to constrain the intrinsic column densities using an absorbed power-law model with Gamma fixed to 1.8. In both cases, the spectral fittings were performed in the 0.3 - 8 keV energy band where the sensitivity of the XMM-Newton detectors is the highest.

Spectral_Index_Pos_Err
The positive error in the power-law photon index, Gamma.

Spectral_Index_Neg_Err
The negative error in the power-law photon index, Gamma.

NH_Limit
The upper or lower limit to the observed best-fit absorption column density, n_H.

NH
The observed best-fit value of the Hydrogen column density, n_H, in atoms cm-2.

NH_Pos_Err
The positive error in the observed best-fit value of the Hydrogen column density, n_H, in atoms cm-2.

NH_Neg_Err
The negative error in the observed best-fit value of the Hydrogen column density, n_H, in atoms cm-2.

Flux
The intrinsic 2 - 8 keV flux of the X-ray source, in erg cm-2 s-1.

Redshift
The redshift (either spectroscopic or photometric according to the value of the opt_ctrprt_flag parameter) of the SDSS counterpart to the X-ray source.

NH_Gal
The Galactic column density in the direction of the observed field, (n_H)_Gal, in atoms cm-2.

Int_Rf_NH
The intrinsic rest-frame column density, (n_H)_Int, in atoms cm-2.

Log_Lx
The logarithm of the intrinsic 2 - 8 keV luminosity of the source, in erg s-1.

Opt_Ctrprt_Flag
This parameter flags the status of the optical counterpart to the X-ray source:

        1 = spectroscopic optical counterpart
        2 = photometric optical counterpart
        3 = absence of an optical counterpart
  

Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 27-Apr-2009