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XSHZAGNCXO - X-Ray Selected High-z AGN Catalog

HEASARC
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Overview

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

2014MNRAS.445.1430K

References

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)

Provenance

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

Parameters

Survey_Code
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.

Name
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.

RA
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.

Dec
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.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Redshift
The spectroscopic redshift of the AGN.

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

Phot_Redshift_Min
The lower limit of the photometric redshift of the AGN.

Phot_Redshift
The measured photometric redshift of the AGN.

Phot_Redshift_Max
The upper limit of the photometric redshift of the AGN.

Optical_Type_Code
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.

Xray_Type_Code
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.

SB_Flux_Code
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).

SB_Flux
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.

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

Hardness_Ratio
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.

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

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

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

NH
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