The Evolution and Eddington Ratio Distribution of Compton Thick Active Galactic Nuclei

Draper, Aden R.; Ballantyne, D. R.

doi:10.1088/2041-8205/715/2/l99

Cited by 52 publications

(115 citation statements)

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“…The model of Gilli et al (2007) is compatible at bright fluxes with the BAT data, but with a steeper slope. On the other hand, there seems to be a constant offset between the BAT log N-logS and the model predictions of Treister et al (2009) and Draper & Ballantyne (2010). The model of Treister et al (2009) reproduces the 14-195 keV BAT log N-log S of Tueller et al (2008) which is in very good agreement with the one published here.…”

Section: Notesupporting

confidence: 87%

“…6 In order to convert the INTEGRAL data to the BAT band, we took into account that 1 BAT-mCrab in the 17-60 keV band is 1.22 × 10 −11 erg cm (2007) model we use the 10-40 keV predictions available online. 7 Since BAT detects very few Compton-thick AGNs, we limited the predictions of the models of Gilli et al (2007) and Draper & Ballantyne (2010) to objects with log N H 24. The predictions by Treister et al (2009) include objects with log N H 24, however, in their modeling the density of Compton-thick AGNs is (at BAT sensitivities) ∼7% of the total AGN population.…”

Section: Notementioning

confidence: 99%

“…The model of Draper & Ballantyne (2010) reproduces (see their Figure 3) the "correct" 14-195 keV log N-log S as reported by Tueller et al (2008). However, their 10-30 keV model prediction is at fluxes 10 −14 erg cm −2 s −1 very similar to the one of Treister et al (2009), and their predicted densities are a factor 1.6-1.8 larger than the measured ones in the 15-55 keV band (see Table 4) at the faintest fluxes sampled by our analysis.…”

Section: Notementioning

confidence: 99%

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THE 60 MONTH ALL-SKY BURST ALERT TELESCOPE SURVEY OF ACTIVE GALACTIC NUCLEUS AND THE ANISOTROPY OF NEARBY AGNs

Ajello

Alexander

Greiner

et al. 2012

ApJ

109

143

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Surveys above 10 keV represent one of the best resources to provide an unbiased census of the population of active galactic nuclei (AGNs). We present the results of 60 months of observation of the hard X-ray sky with Swift/Burst Alert Telescope (BAT). In this time frame, BAT-detected (in the 15-55 keV band) 720 sources in an all-sky survey of which 428 are associated with AGNs, most of which are nearby. Our sample has negligible incompleteness and statistics a factor of ∼2 larger over similarly complete sets of AGNs. Our sample contains (at least) 15 bona fide Compton-thick AGNs and 3 likely candidates. Compton-thick AGNs represent ∼5% of AGN samples detected above 15 keV. We use the BAT data set to refine the determination of the log N-log S of AGNs which is extremely important, now that NuSTAR prepares for launch, toward assessing the AGN contribution to the cosmic X-ray background. We show that the log N-log S of AGNs selected above 10 keV is now established to ∼10% precision. We derive the luminosity function of Compton-thick AGNs and measure a space density of 7.9 +4.1 −2.9 × 10 −5 Mpc −3 for objects with a de-absorbed luminosity larger than 2 × 10 42 erg s −1 . As the BAT AGNs are all mostly local, they allow us to investigate the spatial distribution of AGNs in the nearby universe regardless of absorption. We find concentrations of AGNs that coincide spatially with the largest congregations of matter in the local ( 85 Mpc) universe. There is some evidence that the fraction of Seyfert 2 objects is larger than average in the direction of these dense regions.

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Section: Notesupporting

confidence: 87%

Section: Notementioning

confidence: 99%

Section: Notementioning

confidence: 99%

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THE 60 MONTH ALL-SKY BURST ALERT TELESCOPE SURVEY OF ACTIVE GALACTIC NUCLEUS AND THE ANISOTROPY OF NEARBY AGNs

Ajello

Alexander

Greiner

et al. 2012

ApJ

109

143

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“…It is worth noting that Draper & Ballantyne (2010) have corrected the local space density reported by Treister et al (2009a) to account for the flux-luminosity relation for Comptonthick AGN described by Rigby et al (2009); they found a value in very good agreement with our estimate (∼3.6 × 10 −6 Mpc −3 ).…”

Section: Comparison With Other Samplessupporting

confidence: 86%

A new technique to efficiently select Compton-thick AGN

Severgnini

Caccianiga

Ceca

2012

A&A

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Aims. We present a new efficient diagnostic method, based on mid-infrared and X-ray data, to select local (z < 0.1) Compton-thick AGN with the aim of estimating their surface and space density. Methods. We define a region in the X-ray-to-mid-IR [F(2−12 keV)/F 25 ν 25 ] vs. X-ray color (HR) plane associated to Compton-thick AGN, i.e. [F(2−12 keV)/F 25 ν 25 ] < 0.02 and HR > −0.2. On the basis of this selection method we build up a sample of 43 Comptonthick AGN candidates using data from IRAS Point Source and 2XMM-Newton catalogues. In order to test the efficiency of the proposed method in selecting Compton-thick AGN we use the results of the X-ray spectral analysis performed on all the sources of our sample (presented in a parallel work). After taking into account the different selection effects, we have estimated the number of Compton-thick in the local Universe and their density down to the IRAS flux limit of F 25 = 0.5 Jy. Results. We find that the diagnostic plot proposed here is an efficient method to select Compton-thick AGN in the nearby Universe since ∼84% of the sources populating the proposed Compton-thick region are actually Compton-thick AGN. Twenty percent are newly-discovered Compton-thick AGN. We then estimate the surface density of Compton-thick AGN down to the IRAS PSC catalogue flux limit (F 25 = 0.5 Jy) that turns out to be ρ CT ∼ 3 × 10 −3 src deg −2 . After estimating an equivalent IR-to-hard-X-ray limiting flux, we compare our result with those found with Swift-BAT. We find that the surface density derived here is a factor 4 above the density computed in the hard X-ray surveys. This difference is ascribed, at least in part, to a significant contribution (∼60−90%) of the star-forming activity to the total 25 μm emission for the sources in our sample. By considering only the 25 μm AGN emission, we estimate a surface density of Compton-thick AGN which is consistent with the results found by hard X-ray surveys. Finally, we estimated the co-moving space density of Compton-thick AGN with intrinsic L X > 10 43 erg s −1 (0.004 < z < 0.06): Φ C−thick ∼ (3.5 +4.5 −0.5 ) × 10 −6 Mpc −3 . The prediction for Compton-thick AGN based on the synthesis model of X-ray background in Gilli et al. (2007) is consistent with this value.

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“…They also allow exploration of the importance of the CT population, although with different constraining power and different non-negligible degrees of bias-especially at the highest column densities and lowest luminosities (e.g., Burlon et al 2011;Brightman et al 2014;Buchner et al 2015;Lanzuisi et al 2015;Ricci et al 2015). Indeed, the large diversity in the spectral shapes, as well as poorly explored observational parameters in low counting regimes 26 such as the high energy cut-off and the reflection strength at high energies (Treister et al 2009;Ballantyne et al 2011, hereafter BA11), the scattered fractions at low energies (Brightman & Ueda 2012;Lanzuisi et al 2015), or physical parameters such as the Eddington ratio (Draper & Ballantyne 2010), may further introduce uncertainty or biases, enlarging the possible range of the fraction of CT sources to an order of magnitude (Akylas et al 2012) or even significantly reducing their importance (Gandhi et al 2007). …”

Section: Introductionmentioning

confidence: 99%

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

Zappacosta

Comastri

Civano

et al. 2018

ApJ

Self Cite

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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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The Evolution and Eddington Ratio Distribution of Compton Thick Active Galactic Nuclei

Cited by 52 publications

References 49 publications

THE 60 MONTH ALL-SKY BURST ALERT TELESCOPE SURVEY OF ACTIVE GALACTIC NUCLEUS AND THE ANISOTROPY OF NEARBY AGNs

THE 60 MONTH ALL-SKY BURST ALERT TELESCOPE SURVEY OF ACTIVE GALACTIC NUCLEUS AND THE ANISOTROPY OF NEARBY AGNs

A new technique to efficiently select Compton-thick AGN

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

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