Compton-thick AGN in the <i>NuSTAR</i> Era X: Analysing seven local CT-AGN candidates

Sengupta, D.; Marchesi, S.; Vignali, C.; Torres-Albà, N.; Bertola, E.; Pizzetti, A.; Lanzuisi, G.; Salvestrini, Francesco; Zhao, X.; Gaspari, M.; Gilli, R.; Comastri, A.; Traina, A.; Tombesi, Francesco; Silver, R.; Pozzi, F.; Ajello, M.

doi:10.1051/0004-6361/202245646

Cited by 5 publications

(1 citation statement)

References 57 publications

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“…In particular, we will be able to determine a solid Compton-thick fraction up to redshift 4 and place constraints up to z∼6. This holds particular importance because current work shows discrepancies in the Compton-thick fraction even in the local universe (e.g., [18,31,33,34]) and, ata high redshift (z > 4), the use of extrapolations or XLFs characterized by notable uncertainties is common due to a lack of strong empirical support.…”

Section: Discussionmentioning

confidence: 97%

X-ray Redshifts for Obscured Active Galactic Nuclei with AXIS Deep and Intermediate Surveys

Peca,

Cappelluti,

Marchesi

et al. 2024

Universe

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This study presents the capabilities of the AXIS telescope in estimating redshifts from X-ray spectra alone (X-ray redshifts, XZs). Through extensive simulations, we establish that AXIS observations enable reliable XZ estimates for more than 5500 obscured active galactic nuclei (AGNs) up to redshift z∼6 in the proposed deep (7 Ms) and intermediate (375 ks) surveys. Notably, at least 1600 of them are expected to be in the Compton-thick regime (logNH/cm−2≥24), underscoring the pivotal role of AXIS in sampling these elusive objects that continue to be poorly understood. XZs provide an efficient alternative for optical/infrared faint sources, overcoming the need for time-consuming spectroscopy, the potential limitations of photometric redshifts, and potential issues related to multi-band counterpart association. This approach will significantly enhance the accuracy of constraints on the X-ray luminosity function and obscured AGN fractions up to high redshifts. This white paper is part of a series commissioned for the AXIS Probe Concept Mission; additional AXIS white papers can be found at the AXIS website.

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Section: Discussionmentioning

confidence: 97%

X-ray Redshifts for Obscured Active Galactic Nuclei with AXIS Deep and Intermediate Surveys

Peca,

Cappelluti,

Marchesi

et al. 2024

Universe

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Modelling molecular clouds and CO excitation in AGN-host galaxies

Esposito,

Vallini,

Pozzi

et al. 2023

Monthly Notices of the Royal Astronomical Society

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We present a new physically motivated model for estimating the molecular line emission in active galaxies. The model takes into account (i) the internal density structure of giant molecular clouds (GMCs), (ii) the heating associated with both stars and the active galactic nuclei (AGNs), respectively, producing photodissociation regions (PDRs) and X-ray-dominated regions (XDRs) within the GMCs, and (iii) the mass distribution of GMCs within the galaxy volume. The model needs, as input parameters, the radial profiles of molecular mass, far-UV flux and X-ray flux for a given galaxy, and it has two free parameters: the CO-to-H2 conversion factor αCO, and the X-ray attenuation column density NH. We test this model on a sample of 24 local (z ≤ 0.06) AGN-host galaxies, simulating their carbon monoxide spectral-line energy distribution (CO SLED). We compare the results with the available observations and calculate, for each galaxy, the best (αCO, NH) with a Markov chain Monte Carlo algorithm, finding values consistent with those present in the literature. We find a median αCO = 4.8 M⊙ (K km s−1 pc2)−1 for our sample. In all the modelled galaxies, we find the XDR component of the CO SLED to dominate the CO luminosity from Jupp ≥ 4. We conclude that, once a detailed distribution of molecular gas density is taken into account, PDR emission at mid-/high-J becomes negligible with respect to XDR.

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The High-Energy X-ray Probe (HEX-P): the circum-nuclear environment of growing supermassive black holes

Boorman,

Torres-Albà,

Annuar

et al. 2024

Front. Astron. Space Sci.

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Ever since the discovery of the first active galactic nuclei (AGN), substantial observational and theoretical effort has been invested into understanding how massive black holes have evolved across cosmic time. Circum-nuclear obscuration is now established as a crucial component, with almost every AGN observed known to display signatures of some level of obscuration in their X-ray spectra. However, despite more than six decades of effort, substantial open questions remain: how does the accretion power impact the structure of the circum-nuclear obscurer? What are the dynamical properties of the obscurer? Can dense circum-nuclear obscuration exist around intrinsically weak AGN? How many intermediate mass black holes occupy the centers of dwarf galaxies? In this paper, we showcase a number of next-generation prospects attainable with the High-Energy X-ray Probe (HEX-P1) to contribute toward solving these questions in the 2030s. The uniquely broad (0.2–80 keV) and strictly simultaneous X-ray passband of HEX-P makes it ideally suited for studying the temporal co-evolution between the central engine and circum-nuclear obscurer. Improved sensitivities and reduced background will enable the development of spectroscopic models complemented by current and future multi-wavelength observations. We show that the angular resolution of HEX-P both below and above 10 keV will enable the discovery and confirmation of accreting massive black holes at both low accretion power and low black hole masses even when concealed by thick obscuration. In combination with other next-generation observations of the dusty hearts of nearby galaxies, HEX-P will be pivotal in paving the way toward a complete picture of black hole growth and galaxy co-evolution.

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Compton-thick AGN in the NuSTAR Era X: Analysing seven local CT-AGN candidates

Cited by 5 publications

References 57 publications

X-ray Redshifts for Obscured Active Galactic Nuclei with AXIS Deep and Intermediate Surveys

X-ray Redshifts for Obscured Active Galactic Nuclei with AXIS Deep and Intermediate Surveys

Modelling molecular clouds and CO excitation in AGN-host galaxies

The High-Energy X-ray Probe (HEX-P): the circum-nuclear environment of growing supermassive black holes

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