The NuSTAR Serendipitous Survey: Hunting for The Most Extreme Obscured AGN at >10 keV

Abstract

We identify sources with extremely hard X-ray spectra (i.e., with photon indices of Gamma<0.6 in the 13 sq. deg. NuSTAR serendipitous survey, to search for the most highly obscured AGNs detected at >10 keV. Eight extreme NuSTAR sources are identified, and we use the NuSTAR data in combination with lower energy X-ray observations (from Chandra, Swift XRT, and XMM-Newton) to characterize the broad-band (0.5-24 keV) X-ray spectra. We find that all of the extreme sources are highly obscured AGNs, including three robust Compton-thick (CT; N_H > 1.5e24 cm^-2) AGNs at low redshift (z<0.1), and a likely-CT AGN at higher redshift (z=0.16). Most of the extreme sources would not have been identified as highly obscured based on the low energy (<10 keV) X-ray coverage alone. The multiwavelength properties (e.g., optical spectra and X-ray/MIR luminosity ratios) provide further support for the eight sources being significantly obscured. Correcting for absorption, the intrinsic rest-frame 10-40 keV luminosities of the extreme sources cover a broad range, from ~ 5 x 10^42 to 10^45 erg s^-1. The estimated number counts of CT AGNs in the NuSTAR serendipitous survey are in broad agreement with model expectations based on previous X-ray surveys, except for the lowest redshifts (z<0.07) where we measure a high CT fraction of f_CT^obs = 30 (+16 -12) %. For the small sample of CT AGNs, we find a high fraction of galaxy major mergers (50 +/- 33%) compared to control samples of "normal" AGNs.

19 pages, 15 figures, 5 tables; Accepted for publication in ApJ; Author list updated

References in corpus (38)

• The Host Galaxies and Classification of Active Galactic Nuclei
• A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies: I. Galaxy Mergers & Quasar Activity
• 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
• Multiwavelength study of massive galaxies at z~2. II. Widespread Compton thick AGN and the concurrent growth of black holes and bulges
• 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
• Unveiling obscured accretion in the Chandra Deep Field South
• Growing supermassive black holes in the late stages of galaxy mergers are heavily obscured
• Merging and Clustering of the Swift BAT AGN Sample
• The X-Ray to Mid-Infrared Relation of AGN at High Luminosity
• Reliable Identification of Compton-thick Quasars at z~2: Spitzer Mid-IR spectroscopy of HDF-oMD49
• NuSTAR and XMM-Newton Observations of Luminous, Heavily Obscured, WISE-Selected Quasars at z ~ 2
• X-rays across the galaxy population I: tracing the main sequence of star formation
• The mid IR -- hard X-ray correlation in AGN and its implications for dusty torus models
• The NuSTAR View of Nearby Compton-thick AGN: The Cases of NGC 424, NGC 1320 and IC 2560
• Revisiting the relationship between 6 μm and 2-10 keV continuum luminosities of AGN
• Compton thick active galactic nuclei in Chandra surveys
• Galaxy gas as obscurer: II. Separating the galaxy-scale and nuclear obscurers of Active Galactic Nuclei
• Compton Thick AGN in the XMM-COSMOS survey
• Weak Hard X-ray Emission from Broad Absorption Line Quasars: Evidence for Intrinsic X-ray Weakness
• NuSTAR unveils a Compton-thick Type 2 quasar in Mrk 34
• Long-Term X-ray Variability of Typical Active Galactic Nuclei in the Distant Universe
• Revealing X-ray obscured quasars in SWIRE sources with extreme mid-IR/optical flux ratios
• The Angular Clustering of Infrared-Selected Obscured and Unobscured Quasars
• Low Resolution Spectral Templates For Galaxies From 0.2 -- 10 microns
• The NuSTAR Serendipitous Survey: The 40 month Catalog and the Properties of the Distant High Energy X-ray Source Population
• Clustering properties of moderate luminosity X-ray selected Type 1 and Type 2 AGN at z~3
• NuSTAR Resolves the First Dual AGN above 10 keV in SWIFT J2028.5+2543
• Compton Thick AGN in the 70 Month Swift-BAT All-Sky Hard X-ray Survey: a Bayesian approach
• Structures in the Great Attractor Region
• The HELLAS2XMM survey: XI. Unveiling the nature of X-ray Bright Optically Normal Galaxies
• The quest for Type 2 quasars: Chandra observations of luminous obscured quasars in the Sloan Digital Sky Survey
• Delving Into X-ray Obscuration of Type 2 AGN, Near and Far
• A New Compton-thick AGN in our Cosmic Backyard: Unveiling the Buried Nucleus in NGC 1448 with NuSTAR
• NuSTAR J033202-2746.8: direct constraints on the Compton reflection in a heavily obscured quasar at z~2
• An investigation of star formation and dust attenuation in major mergers using ultraviolet and infrared data
• The Phoenix galaxy as seen by NuSTAR

Cited by in corpus (31)

• BAT AGN Spectroscopic Survey - V. X-ray properties of the Swift/BAT 70-month AGN catalog
• BASS XXV: DR2 Broad-line Based Black Hole Mass Estimates and Biases from Obscuration
• Comprehensive Broadband X-ray and Multiwavelength Study of Active Galactic Nuclei in Local 57 Ultra/luminous Infrared Galaxies Observed with NuSTAR and/or Swift/BAT
• The properties of the AGN torus as revealed from a set of unbiased NuSTAR observations
• Buried Black Hole Growth in IR-selected Mergers: New Results from Chandra
• Piercing Through Highly Obscured and Compton-thick AGNs in the Chandra Deep Fields: I. X-ray Spectral and Long-term Variability Analyses
• Completing the Census of AGN in GOODS-S/HUDF: New Ultra-Deep Radio Imaging and Predictions for JWST
• Local AGN Survey (LASr): I. Galaxy sample, infrared colour selection and predictions for AGN within 100 Mpc
• Hard X-Ray to Radio Multiwavelength SED Analysis of Local U/LIRGs in GOALS Sample with Self-consistent AGN Model Including Polar-dust Component
• A Large Population of Luminous Active Galactic Nuclei Lacking X-ray Detections: Evidence for Heavy Obscuration?
• The Dust-to-Gas Ratio and the Role of Radiation Pressure in Luminous, Obscured Quasars
• Disentangling the Complex Broadband X-ray Spectrum of IRAS 13197-1627 with NuSTAR, XMM-Newton and Suzaku
• Accretion History of AGN II: Constraints on AGN Spectral Parameters using the Cosmic X-ray Background
• A High Fraction of Heavily X-ray Obscured Active Galactic Nuclei
• Accretion History of AGN III: Radiative Efficiency and AGN Contribution to Reionization
• Broad-band X-ray analysis of local mid-infrared selected Compton-thick AGN candidates
• The Most Obscured AGNs in the XMM-SERVS Fields
• Obscured AGN enhancement in galaxy pairs at cosmic noon: evidence from a probabilistic treatment of photometric redshifts
• A Multi-wavelength search for Black Widows and Redbacks counterparts of candidate $\gamma$-ray millisecond pulsars
• The Star-Formation Properties of the Observed and Simulated AGN Universe: BAT vs EAGLE
• The role of SPICA-like missions and the Origins Space Telescope in the quest for heavily obscured AGN and synergies with Athena
• Multi-wavelength Selected Compton-thick AGNs in Chandra Deep Field-South Survey
• A broadband X-ray imaging spectroscopy in the 2030s: the FORCE mission
• A broadband X-ray view of the NLSy1 1E 0754.6+392.8
• Warm absorbers: supermassive black hole feeding, and Compton-thick AGN
• A population of Optically Quiescent Quasars from WISE and SDSS
• Infrared Colours and Spectral Energy Distributions of Hard X-ray Selected Obscured and Compton-thick AGN
• The Compton-thick AGN luminosity function in the local Universe: A robust estimate combining BAT detections and NuSTAR spectra
• Active Galactic Nuclei and their demography through cosmic time
• X-ray Absorption and Reprocessing in the $z\sim 2.5$ Lensed Quasar 2MASS J1042+1641
• BASS XLV: Quantifying AGN Selection Effects in the Chandra COSMOS-Legacy Survey with BASS