Compton-thick AGN in the NuSTAR Era VI: The Observed Compton-thick Fraction in the Local Universe

Torres-Albà, N.; Marchesi, S.; Zhao, X.; Ajello, M.; Silver, R.; Ananna, Tonima Tasnim; Baloković, Mislav; Boorman, Peter; Comastri, A.; Gilli, R.; Lanzuisi, G.; Murphy, Kendrah D.; Urry, C. M.; Vignali, C.

doi:10.3847/1538-4357/ac1c73

Cited by 28 publications

(26 citation statements)

References 70 publications

(96 reference statements)

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“…Moreover, Asmus et al ( 2015) used a sample of 152 AGN with reliable soft X-ray data to model a trend between the intrinsic 2−10 keV luminosity and the 12µm luminosity (see Figure 3). In addition, we have plotted the intrinsic (closed circles) and observed (open circles) X-ray luminosities of the sources in this work, and those of recently confirmed CT-AGN (Marchesi et al 2019;Zhao et al 2019a,b;Torres-Albà et al 2021;Traina et al 2021). The two green stars represent the candidate CT-AGN presented in this work, 2MASX J02051994−0233055 and IRAS 11058−1131.…”

Section: Mid-ir Comparisonmentioning

confidence: 89%

“…We take advantage of our high-resolution Chandra images and attempt to detect the cone emission in the highly obscured sources presented in this work. In order to do so, we extract radial profiles from all of our sources and compare them to the expected radial profile The blue circles are recently confirmed CT-AGN (Marchesi et al 2019;Zhao et al 2019a,b;Torres-Albà et al 2021;Traina et al 2021). The grey area represents a 25× (or more) decrease in X-ray flux, a diagnostic used to identify CT-AGN (Annuar et al 2020).…”

Section: Study Of Extended Emissionmentioning

confidence: 99%

“…The green stars are the two candidate CT-AGN presented in this work, 2MASX J02051994−0233055 and IRAS 11058−1131. The black line is the relation derived from the X-ray observations of a reliable sample of 152 AGN presented in Asmus et al (2015).The blue circles are recently confirmed CT-AGN(Marchesi et al 2019; Zhao et al 2019a,b;Torres- Albà et al 2021;Traina et al 2021). The grey area represents a 25× (or more) decrease in X-ray flux, a diagnostic used to identify CT-AGN(Annuar et al 2020).…”

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confidence: 97%

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Chandra Follow-up Observations of Swift-BAT-selected AGNs II

Silver,

Torres-Alba,

Zhao

et al. 2022

Preprint

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We present the combined Chandra and Swift-BAT spectral analysis of nine low-redshift (z ≤ 0.10), candidate heavily obscured active galactic nuclei (AGN) selected from the Swift-BAT 150-month catalog. We located soft (1−10 keV) X-ray counterparts to these BAT sources and joint fit their spectra with physically motivated models. The spectral analysis in the 1−150 keV energy band determined that all sources are obscured, with a line-of-sight column density N H ≥ 10 22 cm −2 at a 90% confidence level. Four of these sources show significant obscuration with N H ≥ 10 23 cm −2 and two additional sources are candidate Compton-thick Active Galactic Nuclei (CT-AGNs) with N H ≥ 10 24 cm −2 . These two sources, 2MASX J02051994-0233055 and IRAS 11058−1131, are the latest addition to the previous 3 CT-AGN candidates found using our strategy for soft X-ray follow-up of BAT sources. In here we present the results of our methodology so far, and analyze the effectiveness of applying different selection criteria to discover CT-AGN in the local Universe. Our selection criteria has a ∼20% success rate of discovering heavily obscured AGN whose CT nature is confirmed by follow-up NuSTAR observations. This is much higher than the ∼5% found in blind surveys.

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Section: Mid-ir Comparisonmentioning

confidence: 89%

Section: Study Of Extended Emissionmentioning

confidence: 99%

mentioning

confidence: 97%

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Chandra Follow-up Observations of Swift-BAT-selected AGNs II

Silver,

Torres-Alba,

Zhao

et al. 2022

Preprint

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“…They used this to model a trend between the intrinsic 2−10 keV luminosity and the 12 μm luminosity (see Figure 3). In addition, we have plotted the intrinsic (solid circles) and observed (open circles) X-ray luminosities of the sources in this work, and those of recently confirmed CT-AGN (Marchesi et al 2019;Zhao et al 2019aZhao et al , 2019bTorres-Albà et al 2021;Traina et al 2021). The two green stars represent the candidate CT-AGN presented in this work, 2MASX J02051994 −0233055 and IRAS 11058−1131.…”

Section: Mid-ir Comparisonmentioning

confidence: 98%

“…However, only 5%−7% of the hard X-ray detected low-z AGNs are classified as CT-AGNs (Comastri 2004;Della et al 2008;Burlon et al 2011;Ricci et al 2015;Lanzuisi et al 2018), which is much lower than those predicted by population synthesis models that aim to explain the CXB (30%-50%; see, e.g., Gilli et al 2007;Ueda et al 2014;Ananna et al 2019). Currently, there are only ∼30-35 NuSTAR-confirmed CT-AGN in the range z 0.05 (Torres-Albà et al 2021). 5 The low number severely limits any science designed to study this population.…”

Section: Introductionmentioning

confidence: 99%

Chandra Follow-up Observations of Swift-BAT-selected AGNs II

Silver

Torres-Albà

Zhao

et al. 2022

ApJ

Self Cite

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We present the combined Chandra and Swift-BAT spectral analysis of nine low-redshift (z ≤ 0.10), candidate heavily obscured active galactic nuclei (AGN) selected from the Swift-BAT 150 month catalog. We located soft (1−10 keV) X-ray counterparts to these BAT sources and joint fit their spectra with physically motivated models. The spectral analysis in the 1−150 keV energy band determined that all sources are obscured, with a line-of-sight column density N H ≥ 1022 cm−2 at a 90% confidence level. Four of these sources show significant obscuration with N H ≥ 1023 cm−2 and two additional sources are candidate Compton-thick Active Galactic Nuclei (CT-AGNs) with N H ≥ 1024 cm−2. These two sources, 2MASX J02051994–0233055 and IRAS 11058−1131, are the latest addition to the previous 3 CT-AGN candidates found using our strategy for soft X-ray follow-up of BAT sources. Here we present the results of our methodology so far, and analyze the effectiveness of applying different selection criteria to discover CT-AGN in the local Universe. Our selection criteria has an ∼20% success rate of discovering heavily obscured AGN whose CT nature is confirmed by follow-up NuSTAR observations. This is much higher than the ∼5% found in blind surveys.

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Supermassive black holes at high redshift are expected to be obscured by their massive host galaxies’ interstellar medium

Gilli¹,

Norman

Calura³

et al. 2022

A&A

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We combine results from deep ALMA observations of massive (M* > 1010 M⊙) galaxies at different redshifts to show that the column density of their interstellar medium (ISM) rapidly increases toward early cosmic epochs. Our analysis includes objects from the ASPECS and ALPINE large programs, as well as individual observations of z ∼ 6 quasar hosts. When accounting for non-detections and correcting for selection effects, we find that the median surface density of the ISM of the massive galaxy population evolves as ∼(1 + z)3.3. This means that the ISM column density toward the nucleus of a z > 3 galaxy is typically > 100 times larger than locally, and it may reach values as high as Compton-thick at z ≳ 6. Remarkably, the median ISM column density is on the same order of what is measured from X-ray observations of large active galactic nucleus (AGN) samples already at z ≳ 2. We have developed a simple analytic model for the spatial distribution of ISM clouds within galaxies, and estimate the total covering factor toward active nuclei when obscuration by ISM clouds on the host scale is added to that of parsec-scale circumnuclear material (the so-called torus). The model includes clouds with a distribution of sizes, masses, and surface densities, and also allows for an evolution of the characteristic cloud surface density with redshift, Σc, * ∝ (1 + z)γ. We show that, for γ = 2, such a model successfully reproduces the increase in the obscured AGN fraction with redshift that is commonly observed in deep X-ray surveys, both when different absorption thresholds and AGN luminosities are considered. Our results suggest that 80–90% of supermassive black holes in the early Universe (z > 6 − 8) are hidden to our view, primarily by the ISM in their hosts. We finally discuss the implications of our results and how they can be tested observationally with current and forthcoming facilities (e.g., VLT, E-ELT, ALMA, and JWST) and with next-generation X-ray imaging satellites. By extrapolating the observed X-ray nebulae around local AGN to the environments of supermassive black holes at high redshifts, we find ≲1″ nebulae impose stringent design constraints on the spatial resolution of any future X-ray imaging Great Observatory in the coming decades.

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Compton-thick AGN in the NuSTAR Era VI: The Observed Compton-thick Fraction in the Local Universe

Cited by 28 publications

References 70 publications

Chandra Follow-up Observations of Swift-BAT-selected AGNs II

Chandra Follow-up Observations of Swift-BAT-selected AGNs II

Chandra Follow-up Observations of Swift-BAT-selected AGNs II

Supermassive black holes at high redshift are expected to be obscured by their massive host galaxies’ interstellar medium

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