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X-Ray Selected High-z AGN Catalog

Metadata Updated: August 30, 2025

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 L<sub>X</sub> = 43.3 - 46.0 erg/s. X-ray hardness ratios show that ~39 per cent of the sources are highly obscured, N<sub>H</sub> > 10<sup>22</sup> cm<sup>-2</sup>, 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/V<sub>max</sub> 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. This table was created by the HEASARC in March 2016 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/445/1430">CDS catalog J/MNRAS/445/1430</a> file tablea1.dat. This is a service provided by NASA HEASARC .

Access & Use Information

Public: This dataset is intended for public access and use. License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

Downloads & Resources

Dates

Metadata Created Date April 11, 2025
Metadata Updated Date August 30, 2025

Metadata Source

Harvested from NASA Data.json

Additional Metadata

Resource Type Dataset
Metadata Created Date April 11, 2025
Metadata Updated Date August 30, 2025
Publisher High Energy Astrophysics Science Archive Research Center
Maintainer
Identifier ivo://nasa.heasarc/xshzagncxo
Data Last Modified 2025-08-27
Category Astrophysics
Public Access Level public
Bureau Code 026:00
Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
Schema Version https://project-open-data.cio.gov/v1.1/schema
Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
Harvest Object Id fc878b40-67db-4a34-ad9b-cec7c543c5b4
Harvest Source Id 58f92550-7a01-4f00-b1b2-8dc953bd598f
Harvest Source Title NASA Data.json
Homepage URL https://heasarc.gsfc.nasa.gov/W3Browse/all/xshzagncxo.html
Program Code 026:000
Source Datajson Identifier True
Source Hash ea7d43f96d384d64a8501d099d36418520a3fc23721be94b5f7f562a0621909a
Source Schema Version 1.1

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