The fraction of Compton-thick sources in an<i>INTEGRAL</i>complete AGN sample

Malizia, A.; Stephen, J. B.; Bassani, L.; Bird, A. J.; Panessa, F.; Ubertini, P.

doi:10.1111/j.1365-2966.2009.15330.x

Cited by 127 publications

(172 citation statements)

References 44 publications

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“…The largest uncertainty in the AGN luminosity function is in the fraction of Compton thick AGN. The fraction of these objects in the local Universe is high: 30-50% of the optically selected Seyfert 2 galaxies can be Compton thick (≈1/4−1/3 of the full AGN population, Risaliti et al (1999), Panessa et al (2006), a result confirmed by hard X-ray selection, see Malizia et al 2009). At higher redshift, the fraction of Compton thick AGN is more uncertain, but it can be as high as one third of the full AGN population (Fiore et al , 2009), or even higher (Daddi et al 2007;Treister et al 2010).…”

Section: Error Budgetsmentioning

confidence: 71%

Faint high-redshift AGN in theChandradeep field south: the evolution of the AGN luminosity function and black hole demography

Fiore

Puccetti²,

Grazian

et al. 2011

A&A

157

172

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Context. We present detection and analysis of faint X-ray sources in the Chandra deep field south (CDFS) using the 4 Ms Chandra observation. Aims. We place constraints on active galactic nuclei (AGN) luminosity functions at z = 3-7, its cosmological evolution, and highredshift black hole and AGN demography. Methods. We use a new detection algorithm, using the entire three-dimensional data-cube (position and energy), and searching for X-ray counts at the position of high-z galaxies in the GOODS-South survey.Results. This optimized technique results in the identification of 54 AGN at z > 3, 29 of which are new detections. Applying stringent completeness criteria, we derive AGN luminosity functions in the redshift bins 3-4, 4-5, and >5.8 and for 42.75 < log L(2-10 keV) < 44.5. We combine this data with the luminous AGN luminosity functions from optical surveys and find that the evolution of the high-z, wide luminosity range luminosity function can be modeled by pure luminosity evolution with L * decreasing from 6.6 × 10 44 erg/s at z = 3 to L * = 2 × 10 44 erg/s at z = 6. We compare the high-z luminosity function with the predictions of theoretical models using galaxy interactions as AGN triggering mechanism. We find that these models are broadly able to reproduce the high-z AGN luminosity functions. Closer agreement is found when we assume a minimum dark matter halo mass for black hole formation and growth. We compare our AGN luminosity functions with galaxy mass functions to derive the high-z AGN duty cycle, using observed Eddington ratio distributions to derive black hole masses. We find that the duty cycle increases with galaxy stellar mass and redshift by a factor of 10-30 from z = 0.25 to z = 4-5. We also report the detection of a large fraction of highly obscured, Compton thick AGN at z > 3 (18 +17 −10 %). Their optical counterparts do not show any reddening and we thus conclude that the size of the X-ray absorber is likely smaller than the dust sublimation radius. We finally report the discovery of a highly star-forming galaxy at z = 3.47, arguing that its X-ray luminosity is likely dominated by stellar sources. If confirmed, this would be one of the farthest objects in which stellar sources have been detected in X-rays.

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Section: Error Budgetsmentioning

confidence: 71%

Faint high-redshift AGN in theChandradeep field south: the evolution of the AGN luminosity function and black hole demography

Fiore

Puccetti²,

Grazian

et al. 2011

A&A

157

172

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“…We note that the latter is based mainly on the optically selected sample of Risaliti et al (1999). Some column densities in this sample were revised by Malizia et al (2009) and we include these updated values in Fig. 4.…”

Section: Discussionmentioning

confidence: 99%

X-ray observations of highly obscuredτ_9.7μm > 1 sources: an efficient method for selecting Compton-thick AGN?

Georgantopoulos

Dasyra²,

Rovilos³

et al. 2011

A&A

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Observations with the IRS spectrograph onboard Spitzer have found many sources with very deep Si features at 9.7 μm, that have optical depths of τ > 1. Since it is believed that a few of these systems in the local Universe are associated with Compton-thick active galactic nuclei (hereafter AGN), we set out to investigate whether the presence of a strong Si absorption feature is a good indicator of a heavily obscured AGN. We compile X-ray spectroscopic observations available in the literature on the optically-thick (τ 9.7 μm > 1) sources from the 12 μm IRAS Seyfert sample. We find that the majority of the high-τ optically confirmed Seyferts (six out of nine) in the 12 μm sample are probably Compton-thick. Thus, we provide direct evidence of a connection between mid-IR optically-thick galaxies and Compton-thick AGN, with the success rate being close to 70% in the local Universe. This is at least comparable to, if not better than, other rates obtained with photometric information in the mid to far-IR, or even mid-IR to X-rays. However, this technique cannot provide complete Compton-thick AGN samples, i.e., there are many Compton-thick AGN that do not display significant Si absorption, with the most notable example being NGC 1068. After assessing the validity of the high 9.7 μm optical-depth technique in the local Universe, we attempt to construct a sample of candidate Compton-thick AGN at higher redshifts. We compile a sample of seven high-τ Spitzer sources in the Great Observatories Origins Deep Survey (GOODS) and five in the Spitzer First-Look Survey. All these have been selected to have no PAH features (EW 6.2 μm < 0.3 μm) to maximise the probability that they are bona-fide AGN. Six out of the seven GOODS sources have been detected in X-rays, while for the five FLS sources only X-ray flux upper limits are available. The high X-ray luminosities (L X > 10 42 erg s −1 ) of the detected GOODS sources corroborates that these are AGN. For FLS, ancillary optical spectroscopy reveals hidden nuclei in two more sources. SED fitting can support the presence of an AGN in the vast majority of sources. Owing to the limited photon statistics, we cannot derive useful constraints from X-ray spectroscopy on whether these sources are Compton-thick. However, the low L X /L 6 μm luminosity ratios, suggest that at least four out of the six detected sources in GOODS may be associated with Compton-thick AGN.

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“…4 Since Compton-thick AGNs are not included in the hard X-ray AGN LF, which may be a fraction of ∼20% of the total AGN population (Malizia et al 2009), the MBH mass densities inferred from the AGN LFs above may be underestimated by 20% and thus for the best match is underestimated by a factor of ∼1.2. 5 We adopt the QSO spectral energy distribution (SED) model constructed by Hopkins et al (2007).…”

Section: The Mass Density Of Massive Black Holes Inferred From Agnsmentioning

confidence: 99%

THE COSMIC EVOLUTION OF MASSIVE BLACK HOLES AND GALAXY SPHEROIDS: GLOBAL CONSTRAINTS AT REDSHIFTz≲ 1.2

Zhang

2012

ApJ

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We study observational constraints on the cosmic evolution of the relationships between massive black hole (MBH) mass (M • ) and stellar mass (M * ,sph ; or velocity dispersion σ ) of a host galaxy/spheroid. Assuming that the M • -M * ,sph (or M • -σ ) relation evolves with redshift as ∝ (1 + z) Γ , the MBH mass density can be obtained from either the observationally determined galaxy stellar mass functions or velocity dispersion distribution functions over redshift z ∼ 0-1.2 for any given Γ. The MBH mass density at different redshifts can also be inferred from the luminosity function of QSOs/active galactic nuclei (AGNs) provided the radiative efficiency is known. By matching the MBH density inferred from galaxies to that obtained from QSOs/AGNs, we find that Γ = 0.64 +0.27 −0.29 for the M • -M * ,sph relation and Γ = −0.21 +0.28 −0.33 for the M • -σ relation, and = 0.11 +0.04 −0.03 . Our results suggest that MBH mass growth precedes bulge mass growth but that the galaxy velocity dispersion does not increase with the mass growth of the bulge after nuclear activity is quenched, which is roughly consistent with the two-phase galaxy formation scenario proposed by Oser et al. in which a galaxy roughly doubles its mass after z = 1 due to accretion and minor mergers while its velocity dispersion drops slightly.

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The fraction of Compton-thick sources in anINTEGRALcomplete AGN sample

Cited by 127 publications

References 44 publications

Faint high-redshift AGN in theChandradeep field south: the evolution of the AGN luminosity function and black hole demography

Faint high-redshift AGN in theChandradeep field south: the evolution of the AGN luminosity function and black hole demography

X-ray observations of highly obscuredτ_9.7μm > 1 sources: an efficient method for selecting Compton-thick AGN?

THE COSMIC EVOLUTION OF MASSIVE BLACK HOLES AND GALAXY SPHEROIDS: GLOBAL CONSTRAINTS AT REDSHIFTz≲ 1.2

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The fraction of Compton-thick sources in anINTEGRALcomplete AGN sample

Cited by 127 publications

References 44 publications

Faint high-redshift AGN in theChandradeep field south: the evolution of the AGN luminosity function and black hole demography

Faint high-redshift AGN in theChandradeep field south: the evolution of the AGN luminosity function and black hole demography

X-ray observations of highly obscuredτ9.7μm > 1 sources: an efficient method for selecting Compton-thick AGN?

THE COSMIC EVOLUTION OF MASSIVE BLACK HOLES AND GALAXY SPHEROIDS: GLOBAL CONSTRAINTS AT REDSHIFTz≲ 1.2

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X-ray observations of highly obscuredτ_9.7μm > 1 sources: an efficient method for selecting Compton-thick AGN?