The NuSTAR Serendipitous Survey: Hunting for the Most Extreme Obscured AGN at &gt;10 keV

Lansbury, G. B.; Alexander, D. M.; Aird, James; Gandhi, P.; Stern, Daniel; Koss, Michael; Lamperti, Isabella; Ajello, M.; Annuar, A.; Assef, Roberto J.; Ballantyne, D. R.; Baloković, Mislav; Bauer, F. E.; Brandt, W. N.; Brightman, Murray; Chen, C.-T. J.; Civano, F.; Comastri, A.; Moro, A. Del; Fuentes, C.; Harrison, Fiona A.; Marchesi, S.; Masini, Alberto; Mullaney, James; Ricci, Cláudio; Saez, C.; Tomsick, John A.; Treister, Ezequiel; Walton, D. J.; Zappacosta, L.

doi:10.3847/1538-4357/aa8176

Cited by 57 publications

(51 citation statements)

References 124 publications

(225 reference statements)

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“…The serendipitous survey will progressively increase its sky coverage, providing crucial help in this regard, especially if backed up by ancillary spectroscopic low-energy X-ray and optical data. Three (likely four) CT AGN have already been found in the 13deg 2 area probed by the first 40 month serendipitous survey sample in Lansbury et al (2017a). This number has to be regarded as lower limit, given the 70% redshift completeness and the hardness ratio approach used to find extremely heavily obscured candidates.…”

Section: Discussionmentioning

confidence: 99%

“…In particular, at low redshift, Civano et al (2015) presented the spectroscopic identification of a local (z 0.04 ) low-luminosity (∼5×10 42 erg s 1 -) CT AGN not previously recognized by either Chandra or XMM-Newton, with a column density N H  10 24 cm 2 -. Lansbury et al (2017a) identified three similar sources at z 0.1 < that have even higher obscuration in the NuSTAR serendipitous survey. At high redshift, Del Moro et al (2014) presented the detection of a heavily absorbed (N 6 10 H 23 =´cm 2 -) quasar at z = 2.…”

Section: Introductionmentioning

confidence: 98%

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The NuSTAR Extragalactic Surveys: X-Ray Spectroscopic Analysis of the Bright Hard-band Selected Sample

Zappacosta

Comastri

Civano

et al. 2018

ApJ

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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 10 14 =´-( -) erg s cm 1 2 --in the multi-tiered NuSTAR extragalactic survey program. The sources span a redshift range z 0 2.1 = -(median z 0.58 á ñ = ). 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 H ), reflection parameter (R), and 10-40keV luminosity (L X ). Heavily obscured ( N log cm 23AGN constitute ∼25% (15-17 sources) and ∼2-3% (1-2 sources) of the sample, respectively. The observed N H distribution agrees fairly well 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 N log cm 20 24AGN is poorly constrained, formally in the range 2-56% (90% upper limit of 66%). We derived a fraction ( f abs ) of obscured AGN ( N log cm 22 24as 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 L log erg s 43.6 44.3agrees 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.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

The NuSTAR Extragalactic Surveys: X-Ray Spectroscopic Analysis of the Bright Hard-band Selected Sample

Zappacosta

Comastri

Civano

et al. 2018

ApJ

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“…NuSTAR (Harrison et al 2013), launched in 2012, is the first on-orbit focusing hard X-ray telescope, and its serendipitous survey has detected 497 sources in the first 40 months of observations (Lansbury et al 2017b; see also Chen et al 2017). Thanks to its revolutionary characteristics, NuSTAR has been very efficient in constraining the properties of heavily obscured AGNs (e.g., Baloković et al 2014;Gandhi et al 2014;Stern et al 2014;Annuar et al 2015Annuar et al , 2017Brightman et al 2015;Koss et al 2015Koss et al , 2016bLansbury et al 2015Lansbury et al , 2017aBoorman et al 2016;Ricci et al 2016aRicci et al , 2016bRicci et al , 2017aRicci et al , 2017b. The recently launched mission AstroSat (Singh et al 2014) carries on board two hard X-ray instruments: the Large Area Xenon Proportional Counters (LAXPC; 3-80 keV) and the cadmiumzinc-telluride coded-mask imager (CZTI, 10-150 keV).…”

Section: Introductionmentioning

confidence: 99%

BAT AGN Spectroscopic Survey. V. X-Ray Properties of the Swift /BAT 70-month AGN Catalog

Ricci

Trakhtenbrot

Koss

et al. 2017

ApJS

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445

719

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Hard X-ray (10 keV) observations of active galactic nuclei (AGNs) can shed light on some of the most obscured episodes of accretion onto supermassive black holes. The 70-month Swift/BAT all-sky survey, which probes the 14-195 keV energy range, has currently detected 838 AGNs. We report here on the broadband X-ray (0.3-150 keV) characteristics of these AGNs, obtained by combining XMM-Newton, Swift/XRT, ASCA, Chandra, and Suzaku observations in the soft X-ray band ( 10  keV) with 70-month averaged Swift/BAT data. The nonblazar AGNs of our sample are almost equally divided into unobscured (N 10 cm H 22 2 < -) and obscured (N 10 cm H 22 2  -) AGNs, and their Swift/BAT continuum is systematically steeper than the 0.3-10 keV emission, which suggests that the presence of a high-energy cutoff is almost ubiquitous. We discuss the main X-ray spectral parameters obtained, such as the photon index, the reflection parameter, the energy of the cutoff, neutral and ionized absorbers, and the soft excess for both obscured and unobscured AGNs.

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“…Second and more importantly, even at such high energies, Compton-thick (CT) obscuration (N H > 1.5 · 10 24 cm −2 ) extinguishes the intrinsic flux by factors of ten and larger, resulting in a detection bias against CT obscured AGN. This last point is a severe problem because the intrinsic fraction of CT-obscured AGN is probably around ∼ 30% (e.g., Ricci et al 2015;Lansbury et al 2017;Georgantopoulos & Akylas 2019, Boorman et al, in prep. ), and possibly even up 50% (Ananna et al 2019; but see Gandhi et al 2007).…”

Section: Selecting Agn In the X-ray Regimementioning

confidence: 99%

“…The real fraction of the CT AGN is still highly uncertain with estimates ranging from 10% to 50% of all AGN (e.g., Burlon et al 2011;Ricci et al 2015;Akylas et al 2016;Lansbury et al 2017;Georgantopoulos & Akylas 2019;Gandhi & Fabian 2003;Gilli et al 2007;Ueda et al 2014;Ananna et al 2019;Boorman et al, in prep.). The effort of building a complete AGN sample, starting with this work, will hopefully help to narrow down the uncertainty on this fraction.…”

Section: On the Ct Agn Fraction And Ct Candidatesmentioning

confidence: 99%

Local AGN survey (LASr): I. Galaxy sample, infrared colour selection, and predictions for AGN within 100 Mpc

Asmus

Greenwell

Gandhi

et al. 2020

Monthly Notices of the Royal Astronomical Society

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In order to answer some of the major open questions in the fields of supermassive black hole (SMBH) and galaxy evolution, a complete census of SMBH growth, i.e., active galactic nuclei (AGN), is required. Thanks to deep all-sky surveys, such as those by the Wide-field Infrared Survey Explorer (WISE) and the Spectrum-Roentgen-Gamma (SRG) missions, this task is now becoming feasible in the nearby Universe. Here, we present a new survey, the Local AGN Survey (LASr), with the goal of identifying AGN unbiased against obscuration and determining the intrinsic Compton-thick (CT) fraction. First, we construct the most complete all-sky sample of galaxies within 100 Mpc from astronomical databases (90% completeness for log(M * /M ) ∼ 9.4), four times deeper than the current local galaxy reference, the Two Micron All-Sky Survey Redshift Survey (2MRS), which turns out to miss ∼ 20% of known luminous AGN. These 49k galaxies serve as parent sample for LASr, called LASr-GPS. It contains 4.3k already known AGN, ≥ 82% of these are estimated to have L nuc (12 µm) < 10 42.3 erg s −1 , i.e., are low-luminosity AGN. As a first method for identifying Seyfert-like AGN, we use WISEbased infrared colours, finding 221 galaxies at L nuc (12 µm) ≥ 10 42.3 erg s −1 to host an AGN at 90% reliability, This includes 61 new AGN candidates and implies and optical type 2 fraction of 50 to 71%. We quantify the efficiency of this technique and estimate the total number of AGN with L int (2-10 keV) ≥ 10 42 erg s −1 in the volume to be 362 +145 −116 (8.6 +3.5 −2.8 × 10 −5 Mpc −3 ). X-ray brightness estimates indicate the CT fraction to be 40-55% to explain the Swift nondetections of the infrared selected objects. One third of the AGN within 100 Mpc remain to be identified and we discuss the prospects for the eROSITA all-sky survey.

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

Cited by 57 publications

References 124 publications

The NuSTAR Extragalactic Surveys: X-Ray Spectroscopic Analysis of the Bright Hard-band Selected Sample

The NuSTAR Extragalactic Surveys: X-Ray Spectroscopic Analysis of the Bright Hard-band Selected Sample

BAT AGN Spectroscopic Survey. V. X-Ray Properties of the Swift /BAT 70-month AGN Catalog

Local AGN survey (LASr): I. Galaxy sample, infrared colour selection, and predictions for AGN within 100 Mpc

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