this table...

XSHZAGNCXO - X-Ray Selected High-z AGN Catalog



This table contains the results from an analysis of the largest high-redshift (z > 3) X-ray-selected active galactic nucleus (AGN) sample to date, combining the Chandra Cosmological Evolution Survey and Chandra Multi-wavelength Project surveys and doubling the previous samples. The sample comprises 209 X-ray-detected AGNs, over a wide range of rest-frame 2-10 keV luminosities log LX = 43.3 - 46.0 erg/s. X-ray hardness ratios show that ~39 per cent of the sources are highly obscured, NH > 1022 cm-2, in agreement with the ~37 per cent of type-2 AGNs found in this sample based on their optical classification. For ~26 per cent of objects, there are mismatched optical and X-ray classifications. Utilizing the 1/Vmax method, the authors confirm that the comoving space density of all luminosity ranges of AGNs decreases with redshift above z > 3 and up to z ~ 7. With a significant sample of AGNs (N = 27) at z > 4, it is found that both source number counts in the 0.5-2 keV band and comoving space density are consistent with the expectation of a luminosity-dependent density evolution (LDDE) model at all redshifts, while they exclude the luminosity and density evolution (LADE) model. The measured comoving space density of type-1 and type-2 AGNs shows a constant ratio between the two types at z > 3. These results for both AGN types at these redshifts are consistent with the expectations of LDDE model.

The high-redshift AGN sample used in this work has been selected from the C-COSMOS X-ray catalog, combining the spectroscopic and photometric information available from the identification catalogue of X-ray C-COSMOS sources (Civano et al. 2011, ApJ, 741, 91; 2012, ApJS, 201, 30) and the ChaMP (Chandra Multi-wavelength Project) X-ray catalog using only the 323 ChaMP ObsIDs overlapping with Sloan Digital Sky Survey (SDSS; Richards et al. 2006, AJ, 131, 2766) DR5 imaging.

Catalog Bibcode



The largest X-ray-selected sample of z>3 AGNs: C-COSMOS and ChaMP.
    Kalfountzou E., Civano F., Elvis M., Trichas M., Green P.
   <Mon. Not. R. Astron. Soc., 445, 1430-1448 (2014)>
   =2014MNRAS.445.1430K    (SIMBAD/NED BibCode)


This table was created by the HEASARC in March 2016 based on the CDS catalog J/MNRAS/445/1430 file tablea1.dat.


This number code indicates in which survey the X-ray source was found: 1 = ChaMP; 2 = C-COSMOS. See Section 2 of the reference paper for more details about these two surveys.

The Chandra source designation, using the prefix '[KCE2014]' for Kalfountzou, Civano, Elvis 2014, and the J2000.0 coordinates in decimal degrees given to a precision of either 10-3 or 10-4 degrees, e.g., 'KCE2014] 005.826-01.048' or '[KCE2014] 359.3544+00.6643', as recommended by the CDS Dictionary of Nomenclature of Celestial Objects.

The Right Ascension of the X-ray source in the selected equinox. This was given in J2000.0 decimal degrees to a precision of either 10-3 or 10-4 degrees in the original table.

The Declination of the X-ray source in the selected equinox. This was given in J2000.0 decimal degrees to a precision of either 10-3 or 10-4 degrees in the original table.

The Galactic Longitude of the X-ray source.

The Galactic Latitude of the X-ray source.

The spectroscopic redshift of the AGN.

This limit parameter is set to '>' if the corresponding parameter value is a lower limit rather than the actual value.

The lower limit of the photometric redshift of the AGN.

The measured photometric redshift of the AGN.

The upper limit of the photometric redshift of the AGN.

The optical type of the sources as determined by the measured full width at half-maximum (FWHM) of the permitted emission lines. Those objects with emission lines having FWHM > 1000 km s-1 are classified as 'optical broad-line' (BLAGN or Type 1), and all others as 'optical non-broad-line' (non-BLAGN or Type 2), i.e. they show narrow emission lines or absorption lines only. The value of the optical_type_code parameter indicates the AGN's optical type: 1 = Type 1 AGN; 2 = Type 2 AGN.

The X-ray type of the sources as determined by the amount of obscuration evident in their X-ray hardness ratio. In this work, the authors adopt NH = 1022 cm-2 as the dividing criterion; AGNs with NH < 1022 cm-2 and NH > 1022 cm-2 are classified as X-ray unobscured (xray_type_code = 1) and obscured (xray_type_code = 2), respectively. This criterion is adopted by many authors, and is known to be generally in good agreement with the optical type.

This HEASARC-created parameter indicates whether the source was detected in the soft 0.5-2.0 keV band (if set to 1) or, failing that, was instead estimated from the hard-band 2-10 keV flux or from the full-band 0.5-10 keV flux (if set to 2).

The 0.5-2 keV flux of the X-ray source, in erg s-1 cm-2, calculated assuming a power-law slope Gamma of 1.8 and the quoted column density.

The 2-10 keV luminosity of the X-ray source, in erg s-1.

The hardness ratio HR of the X-ray source, defined as HR = (H - S)/(H + S), where S is the 0.5-2.0 keV count rate and H is the 2-10 keV count rate.

The lower limit of the hardness ratio of the X-ray source.

The upper limit of the hardness ratio of the X-ray source.

This parameter is set if the quoted absorption column density is an upper or lower limit to its actual value.

The absorption column density to the X-ray source, in cm-2.

Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 18-Mar-2016