The NuSTAR Extragalactic Surveys: X-ray spectroscopic analysis of the bright hard-band selected sample

Abstract

We discuss the spectral analysis of a sample of 63 Active Galactic Nuclei (AGN) detected above a limiting flux of $S(8-24$ keV$)=7\times 10^{-14}$ erg/s/cm${}^2$ in the multi-tiered NuSTAR Extragalactic Survey program. The sources span a redshift range z=0-2.1 (median $⟨$z$⟩=$0.58). The spectral analysis is performed over the broad 0.5-24 keV energy range, combining NuSTAR with Chandra and/or XMM-Newton data and employing empirical and physically motivated models. This constitutes the largest sample of AGN selected at $>10$ keV to be homogeneously spectrally analyzed at these flux levels. We study the distribution of spectral parameters such as photon index, column density ($N_{\mathrm{H}}$), reflection parameter ($R$) and 10-40 keV luminosity ($L_X$). Heavily obscured ($\log [N_{\mathrm{H}}/c{m}^{-2}]\ge 23$) and Compton Thick (CT; $\log [N_{\mathrm{H}}/c{m}^{-2}]\ge 24$) AGN constitute $\sim$25% (15-17 sources) and $\sim$2-3% ( 1-2 sources) of the sample, respectively. The observed $N_{\mathrm{H}}$ distribution fairly agrees with predictions of Cosmic X-ray Background population synthesis models (CXBPSM). We estimate the intrinsic fraction of AGN as a function of $N_H$, accounting for the bias against obscured AGN in a flux-selected sample. The fraction of CT AGN relative to $\log [N_{\mathrm{H}}/c{m}^{-2}]=20-24$ AGN is poorly constrainted, formally in the range 2-56% (90% upper limit of 66%). We derived a fraction ($f_{abs}$) of obscured AGN ($\log [N_{\mathrm{H}}/c{m}^{-2}]=22-24$) as a function of $L_X$ in agreement with CXBPSM and previous z < 1 X-ray determinations. Furthermore $f_{abs}$ at z=0.1-0.5 and $\log (L_X/erg$ $s^{-1})\approx 43.6-44.3$ agrees with observational measurements/trends obtained over larger redshift intervals. We report a significant anti-correlation of $R$ with $L_X$ (confirmed by our companion paper on stacked spectra) with considerable scatter around the median $R$ values.

Comments: 38 pages, 17 figures, 8 tables. Accepted for publication in ApJ

References in corpus (27)

• The synthesis of the cosmic X-ray background in the Chandra and XMM-Newton era
• 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
• The Chandra Deep Field-South Survey: 7 Ms Source Catalogs
• The Chandra COSMOS Survey, I: Overview and Point Source Catalog
• X-ray spectral properties of AGN in the Chandra Deep Field South
• Cosmic X-ray Surveys of Distant Active Galaxies: The Demographics, Physics, and Ecology of Growing Supermassive Black Holes
• Obscuration-dependent evolution of Active Galactic Nuclei
• NuSTAR Observations of the Bullet Cluster: Constraints on Inverse Compton Emission
• INTEGRAL/IBIS all-sky survey in hard X-rays
• The XMM-Newton wide-field survey in the COSMOS field II: X-ray data and the logN-logS
• The Evolution of Obscuration in AGN
• Seyfert galaxies in the local Universe (z$\le$ 0.1): the average X-ray spectrum as seen by $BeppoSAX$
• The Chandra COSMOS-Legacy survey: Source X-ray spectral properties
• The XMM-Newton wide-field survey in the COSMOS field. IV: X-ray spectral properties of Active Galactic Nuclei
• Compton thick active galactic nuclei in Chandra surveys
• The cosmological properties of AGN in the XMM-Newton Hard Bright Survey
• The Chandra COSMOS legacy survey: Energy Spectrum of the Cosmic X-ray Background and constraints on undetected populations
• The Hard X-Ray Luminosity Function of High-Redshift ($3<z\lesssim 5$) Active Galactic Nuclei
• BAT X-ray Survey - III: X-ray Spectra and Statistical Properties
• Compton Thick AGN in the XMM-COSMOS survey
• The NuSTAR Serendipitous Survey: The 40 month Catalog and the Properties of the Distant High Energy X-ray Source Population
• The NuSTAR Serendipitous Survey: Hunting for The Most Extreme Obscured AGN at >10 keV
• Constraints on light bending and reflection from the hard X-ray background
• A direct comparison of X-ray spectral models for tori in active galactic nuclei
• NuSTAR J033202-2746.8: direct constraints on the Compton reflection in a heavily obscured quasar at z~2
• Chandra and Spitzer observations of CDFS X-ray obscured QSOs
• The NuSTAR Extragalactic Survey: Average broad-band X-ray spectral properties of the NuSTAR detected AGN

Cited by in corpus (34)

• The Accretion History of AGN I: Supermassive Black Hole Population Synthesis Model
• Supermassive Black Holes at High Redshift are Expected to be Obscured by their Massive Host Galaxies' Inter Stellar Medium
• The Chandra COSMOS Legacy Survey: Compton Thick AGN at high redshift
• BASS XXXVII: The role of radiative feedback in the growth and obscuration properties of nearby supermassive black holes
• The properties of the AGN torus as revealed from a set of unbiased NuSTAR observations
• Chasing the observational signatures of seed black holes at z > 7: candidate observability
• Chasing the observational signatures of seed black holes at z > 7: candidate statistics
• Prospects for differentiating extended coronal geometries in AGNs with the IXPE mission
• HYPerluminous quasars at the Epoch of ReionizatION (HYPERION). A new regime for the X-ray nuclear properties of the first quasars
• Examining the Physical Conditions of a Warm Corona in Active Galactic Nuclei Accretion Discs
• BAT AGN Spectroscopic Survey XXVII: Scattered X-Ray Radiation in Obscured Active Galactic Nuclei
• The NuSTAR Extragalactic Surveys: source catalog and the Compton-thick fraction in the UDS field
• The hyperluminous Compton-thick $z\sim 2$ quasar nucleus of the hot DOG W1835+4355 observed by NuSTAR
• Sustaining a Warm Corona in Active Galactic Nuclei Accretion Discs
• Reflection geometries in absorbed and unabsorbed AGN
• Nustar Measurement Of Coronal Temperature In Two Luminous, High Redshift Qsos
• NuSTAR view of Swift/BAT AGN: The $R$-$\Gamma$ correlation
• Accretion History of AGN II: Constraints on AGN Spectral Parameters using the Cosmic X-ray Background
• Correlation between relativistic reflection fraction and photon index in NuSTAR sample of Seyfert 1 AGN
• Broad-band X-ray analysis of local mid-infrared selected Compton-thick AGN candidates
• The properties of the X-ray corona in the distant ($z=3.91$) quasar APM 08279+5255
• The infrared-luminous progenitors of high-z quasars
• Do stellar-mass and super-massive black holes have similar dining habits?
• The Extragalactic Serendipitous Swift Survey (ExSeSS) -- I. Survey definition and measurements of the X-ray number counts
• HYPERION: broad-band X-ray-to-near-infrared emission of Quasars in the first billion years of the Universe
• Breaking the rules at $z\simeq$0.45: the rebel case of RBS 1055
• The source number counts at high energies: SWIFT vs. NuSTAR
• A Chandra X-ray Survey of Optically Selected Close Galaxy Pairs: Unexpectedly Low Occupation of Active Galactic Nuclei
• NuSTAR view of heavily absorbed AGN: The $R-N_{\text{H}}$ correlation
• Correlated variability of the reflection fraction with the X-ray flux and spectral index for Mkn 478
• NuSTAR reveals that the heavily obscured nucleus of NGC 2785 was the contaminant of IRAS 09104+4109 in the BeppoSAX/PDS hard X-rays
• Self-consistent population synthesis of AGN from observational constraints in the X-rays
• The $N_H$ Distribution of Hard X-ray Selected AGN in the NEP Field
• A broadband X-ray study of a sample of AGNs with [OIII] measured inclinations