The high-redshift (z>3) AGN population in the 4 Ms Chandra Deep Field South

Abstract

We present results from a spectral analysis of a sample of high-redshift (z>3) X-ray selected AGN in the 4 Ms Chandra Deep Field South (CDF-S), the deepest X-ray survey to date. The sample is selected using the most recent spectroscopic and photometric information available in this field. It consists of 34 sources with median redshift z=3.7, 80 median net counts in the 0.5-7 keV band and median rest-frame absorption-corrected luminosity $L_{2-10 \rmn{keV}}\approx1.5\times10^{44}\rmn{erg} \rmn{s^{-1}}$. Spectral analysis for the full sample is presented and the intrinsic column density distribution, corrected for observational biases using spectral simulations, is compared with the expectations of X-ray background (XRB) synthesis models. We find that $\approx 57$ per cent of the sources are highly obscured ($N_H>10^{23}\rmn{cm^{-2}}$). Source number counts in the $0.5-2\rmn{keV}$ band down to flux $F_{0.5-2 \rmn{keV}}\approx4\times10^{-17}\rmn{erg} \rmn{s^{-1}cm^{-2}}$ are also presented. Our results are consistent with a decline of the AGN space density at z>3 and suggest that, at those redshifts, the AGN obscured fraction is in agreement with the expectations of XRB synthesis models.

18 pages, 44 figures, a few references added, a few changes made to match the printed version

References in corpus (16)

• A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies: I. Galaxy Mergers & Quasar Activity
• A luminous quasar at a redshift of z = 7.085
• The synthesis of the cosmic X-ray background in the Chandra and XMM-Newton era
• Massive molecular outflows and negative feedback in ULIRGs observed by Herschel-PACS
• X-ray spectral properties of AGN in the Chandra Deep Field South
• Photometric redshift and classification for the XMM-COSMOS sources
• Absorption Properties and Evolution of Active Galactic Nuclei
• Multiwavelength study of massive galaxies at z~2. II. Widespread Compton thick AGN and the concurrent growth of black holes and bulges
• Accretion onto the First Stellar Mass Black Holes
• The Multiwavelength Survey by Yale-Chile (MUSYC): Deep Medium-Band optical imaging and high quality 32-band photometric redshifts in the ECDF-S
• The Great Observatories Origins Deep Survey. VLT/VIMOS Spectroscopy in the GOODS-South Field
• The Evolution of Obscuration in AGN
• A Public, K-Selected, Optical-to-Near-Infrared Catalog of the Extended Chandra Deep Field South (ECDFS) from the MUltiwavelength Survey by Yale-Chile (MUSYC)
• The evolution of the specific star formation rate of massive galaxies to z ~ 1.8 in the E-CDFS
• Six more quasars at redshift 6 discovered by the Canada-France High-z Quasar Survey
• High redshift quasars in the COSMOS survey: the space density of z>3 X-ray selected QSOs

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• Toward the Standard Population Synthesis Model of the X-Ray Background: Evolution of X-Ray Luminosity and Absorption Functions of Active Galactic Nuclei Including Compton-Thick Populations
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• Faint AGNs at z>4 in the CANDELS GOODS-S field: looking for contributors to the reionization of the Universe
• High-redshift AGN in the Chandra Deep Fields: the obscured fraction and space density of the sub-$L_{\ast }$ population
• The Hard X-Ray Luminosity Function of High-Redshift ($3<z\lesssim 5$) Active Galactic Nuclei
• Observational Signatures of High-Redshift Quasars and Local Relics of Black Hole Seeds
• The deepest X-ray view of high-redshift galaxies: constraints on low-rate black-hole accretion
• The systematic search for $z\gtrsim 5$ active galactic nuclei in the $Chandra$ Deep Field South
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• The Chandra Deep Fields: Lifting the Veil on Distant Active Galactic Nuclei and X-Ray Emitting Galaxies
• Faint progenitors of luminous $z\sim 6$ quasars: why don't we see them?
• The Chandra COSMOS Legacy survey: the z>3 sample
• Galaxy-scale Bars in Late-type Sloan Digital Sky Survey Galaxies Do Not Influence the Average Accretion Rates of Supermassive Black Holes
• GA-NIFS: Early-stage feedback in a heavily obscured AGN at $z=4.76$
• The Largest X-ray Selected Sample of z>3 AGNs: C-COSMOS & ChaMP
• The space density of Compton-thick AGN at z~0.8 in the zCOSMOS-Bright Survey
• Exploring Gravitationally-Lensed $z\gtrsim 6$ X-ray AGN Behind the RELICS clusters
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