The NuSTAR Extragalactic Survey: A First Sensitive Look at the High-Energy Cosmic X-ray Background Population

Abstract

We report on the first ten identifications of sources serendipitously detected by the NuSTAR to provide the first sensitive census of the cosmic X-ray background (CXB) source population at >10 keV. We find that these NuSTAR-detected sources are ~100x fainter than those previously detected at >10 keV and have a broad range in redshift and luminosity (z=0.020-2.923 and L_10-40 keV~4x10^{41}-5x10^{45} erg/s); the median redshift and luminosity are z~0.7 and L_10-40 keV~3x10^{44} erg/s, respectively. We characterize these sources on the basis of broad-band ~0.5-32 keV spectroscopy, optical spectroscopy, and broad-band ultraviolet-to-mid-infrared SED analyzes. We find that the dominant source population is quasars with L_10-40 keV>10^{44} erg/s, of which ~50% are obscured with N_H>10^{22} cm^{-2}. However, none of the ten NuSTAR sources are Compton thick (N_H>10^{24} cm^{-2}) and we place a 90% confidence upper limit on the fraction of Compton-thick quasars (L_10-40 keV>10^{44} erg/s) selected at >10 keV of ~33% over the redshift range z=0.5-1.1. We jointly fitted the rest-frame ~10-40 keV data for all of the non-beamed sources with L_10-40 keV>10^{43} erg/s to constrain the average strength of reflection; we find R<1.4 for Γ=1.8, broadly consistent with that found for local AGNs observed at >10 keV. We also constrain the host galaxy masses and find a median stellar mass of ~10^{11} M_sun, a factor ~5 times higher than the median stellar mass of nearby high-energy selected AGNs, which may be at least partially driven by the order of magnitude higher X-ray luminosities of the NuSTAR sources. Within the low source-statistic limitations of our study, our results suggest that the overall properties of the NuSTAR sources are broadly similar to those of nearby high-energy selected AGNs but scaled up in luminosity and mass.

ApJ, in press; 22 pages, 12 figures, 5 tables

References in corpus (24)

• The Cosmic Evolution Survey (COSMOS) -- Overview
• The synthesis of the cosmic X-ray background in the Chandra and XMM-Newton era
• The XMM-Newton Serendipitous Survey. V. The Second XMM-Newton Serendipitous Source Catalogue
• The 105 month Swift-BAT all-sky hard X-ray survey
• Absorption Properties and Evolution of Active Galactic Nuclei
• The XMM-Newton wide-field survey in the COSMOS field: I. Survey description
• Swift BAT Survey of AGN
• The First Hyper-Luminous Infrared Galaxy Discovered by WISE
• INTEGRAL/IBIS all-sky survey in hard X-rays
• The Evolution of Obscuration in AGN
• Seyfert galaxies in the local Universe (z$\le$ 0.1): the average X-ray spectrum as seen by $BeppoSAX$
• Reliable Identification of Compton-thick Quasars at z~2: Spitzer Mid-IR spectroscopy of HDF-oMD49
• AEGIS: New Evidence Linking Active Galactic Nuclei to the Quenching of Star Formation
• The Chandra Deep Protocluster Survey: Ly-alpha Blobs are powered by heating, not cooling
• XMM and Chandra measurements of the AGN intrinsic absorption: dependence on luminosity and redshift
• XMM-Newton observations of the Lockman Hole: X-ray source catalogue and number counts
• Weak Hard X-ray Emission from Two Broad Absorption Line Quasars Observed with NuSTAR: Compton-thick Absorption or Intrinsic X-ray Weakness?
• Low Resolution Spectral Templates For Galaxies From 0.2 -- 10 microns
• Low accretion rates at the AGN cosmic downsizing epoch
• The Host Galaxies and Black Holes of Typical z~0.5-1.4 AGN
• The XMM-Newton bright serendipitous survey. Identification and optical spectral properties
• BAT X-ray Survey - I: Methodology and X-ray Identification
• The deep look onto the hard X-ray sky: The Swift - INTEGRAL X-ray (SIX) survey
• The 26 year-long X-ray light curve and the X-ray spectrum of the BL Lac Object 1E 1207.9+3945 in its brightest state

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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
• BAT AGN Spectroscopic Survey - V. X-ray properties of the Swift/BAT 70-month AGN catalog
• Cosmic X-ray Surveys of Distant Active Galaxies: The Demographics, Physics, and Ecology of Growing Supermassive Black Holes
• Compton-thick Accretion in the local Universe
• Obscuration-dependent evolution of Active Galactic Nuclei
• AGN Type-casting: Mrk 590 No Longer Fits the Role
• The Accretion History of AGN I: Supermassive Black Hole Population Synthesis Model
• The X-Ray to Mid-Infrared Relation of AGN at High Luminosity
• NuSTAR and XMM-Newton Observations of Luminous, Heavily Obscured, WISE-Selected Quasars at z ~ 2
• Detailed Shape and Evolutionary Behavior of the X-ray Luminosity Function of Active Galactic Nuclei
• The NuSTAR View of Nearby Compton-thick AGN: The Cases of NGC 424, NGC 1320 and IC 2560
• The cosmic growth of the active black hole population at 1<z<2 in zCOSMOS, VVDS and SDSS
• Compton thick active galactic nuclei in Chandra surveys
• Compton Thick AGN in the XMM-COSMOS survey
• Weak Hard X-ray Emission from Broad Absorption Line Quasars: Evidence for Intrinsic X-ray Weakness
• Black-Hole Growth is Mainly Linked to Host-Galaxy Stellar Mass rather than Star Formation Rate
• NuSTAR unveils a Compton-thick Type 2 quasar in Mrk 34
• The NuSTAR Extragalactic Surveys: The Number Counts of Active Galactic Nuclei and the Resolved Fraction of the Cosmic X-ray Background
• Relationship between star formation rate and black hole accretion at z=2: The different contributions in quiescent, normal and starburst galaxies
• NuSTAR Reveals Extreme Absorption in z < 0.5 Type 2 Quasars
• The NuSTAR Extragalactic Surveys: Overview and Catalog from the COSMOS Field
• NuSTAR observations of WISE J1036+0449, a Galaxy at z$\sim 1$ obscured by hot dust
• NuSTAR Observations of Heavily Obscured Quasars at z ~ 0.5
• The NuSTAR Serendipitous Survey: The 40 month Catalog and the Properties of the Distant High Energy X-ray Source Population
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• BASS XXXVII: The role of radiative feedback in the growth and obscuration properties of nearby supermassive black holes
• NuSTAR Reveals the Comptonizing Corona of the Broad-Line Radio Galaxy 3C 382
• The NuSTAR Extragalactic Surveys: First Direct Measurements of the >10 keV X-Ray Luminosity Function for Active Galactic Nuclei at z>0.1
• The Chandra Deep Fields: Lifting the Veil on Distant Active Galactic Nuclei and X-Ray Emitting Galaxies
• The NuSTAR Serendipitous Survey: Hunting for The Most Extreme Obscured AGN at >10 keV
• A simplified view of blazars: contribution to the X-ray and gamma-ray cosmic backgrounds
• The NuSTAR Extragalactic Surveys: Initial Results and Catalog from the Extended Chandra Deep Field South
• The NuSTAR Extragalactic Surveys: X-ray spectroscopic analysis of the bright hard-band selected sample
• NuSTAR observations and broadband spectral energy distribution modeling of the millisecond pulsar binary PSR J1023+0038
• AGN-enhanced outflows of low-ionization gas in star-forming galaxies at 1.7<z<4.6
• A broadband X-ray study of the Geminga pulsar with NuSTAR and XMM-Newton
• X-ray constraints on the fraction of obscured AGN at high accretion luminosities
• X-ray Observations of Luminous Dusty Quasars at z > 2
• A UV to Mid-IR Study of AGN Selection
• The NuSTAR Extragalactic Surveys: source catalog and the Compton-thick fraction in the UDS field
• Hard X-ray selected AGNs in low-mass galaxies from the NuSTAR serendipitous survey
• NuSTAR J033202-2746.8: direct constraints on the Compton reflection in a heavily obscured quasar at z~2
• The demographics of obscured AGN from X-ray spectroscopy guided by multiwavelength information
• NuSTAR measurement of the cosmic X-ray background in the 3-20 keV energy band
• The space density of Compton-thick AGN at z~0.8 in the zCOSMOS-Bright Survey
• The NuSTAR Extragalactic Survey: Average broad-band X-ray spectral properties of the NuSTAR detected AGN
• NuSTAR and Keck Observations of Heavily Obscured Quasars Selected by WISE
• Mildly obscured active galaxies and the cosmic X-ray background
• Searching for highly obscured AGN in the XMM-Newton serendipitous source catalog
• Can AGN and galaxy clusters explain the surface brightness fluctuations of the cosmic X-ray background?
• Hard X-ray/Soft gamma-ray experiments and missions: overview and prospects
• Galactic Sources Detected in the NuSTAR Serendipitous Survey
• Surveys of the Cosmic X-ray Background
• The eROSITA Final Equatorial Depth Survey (eFEDS): the hard X-ray selected sample
• Compton-thick active galactic nuclei from the 7 Ms observation in the Chandra Deep Field South
• The NuSTAR Extragalactic Surveys: unveiling rare, buried AGNs and detecting the contributors to the peak of the Cosmic X-ray Background
• Studying the ICM in clusters of galaxies via surface brightness fluctuations of the cosmic X-ray background
• The Extragalactic Serendipitous Swift Survey (ExSeSS) -- I. Survey definition and measurements of the X-ray number counts
• The composite X-ray spectrum of 3CRR Quasars
• The Complex X-ray Obscuration Environment in the Radio Loud Type 2 Quasar 3C 223
• Obscured accretion from AGN surveys
• X-ray selection of Compton Thick AGN at high redshift
• BASS XLV: Quantifying AGN Selection Effects in the Chandra COSMOS-Legacy Survey with BASS
• The study of the circumnuclear environment of accreting supermassive black holes with realistic X-ray spectral models
• An XMM-Newton Analysis of the Supermassive Black Hole Binary Candidate MCG+11--11--032
• The $N_H$ Distribution of Hard X-ray Selected AGN in the NEP Field
• The $\text{NuSTAR}$ Extragalactic Surveys: Source Catalogs from the Extended $\text{Chandra}$ Deep Field-South and the $\text{Chandra}$ Deep Field-North
• A Serendipitous Hard X-ray Detection of the Blazar LBQS 1319+0039