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Probing the roles of orientation and multi-scale gas distributions in shaping the obscuration of Active Galactic Nuclei through cosmic time

Probing the roles of orientation and multi-scale gas distributions in shaping the obscuration of Active Galactic Nuclei through cosmic time
Probing the roles of orientation and multi-scale gas distributions in shaping the obscuration of Active Galactic Nuclei through cosmic time
The origin of obscuration in Active Galactic Nuclei (AGN) is still an open debate. In particular, it is unclear what drives the relative contributions to the line-of-sight column densities from galaxy-scale and torus-linked obscuration. The latter source is expected to play a significant role in Unification Models, while the former is thought to be relevant in both Unification and Evolutionary Models. In this work, we make use of a combination of cosmological semi-analytic models and semi-empirical prescriptions for the properties of galaxies and AGN, to study AGN obscuration. We consider a detailed object-by-object modelling of AGN evolution, including different AGN light curves (LCs), gas density profiles, and also AGN feedback-induced gas cavities. Irrespective of our assumptions on specific AGN LC or galaxy gas fractions, we find that, on the strict assumption of an exponential profile for the gas component, galaxy-scale obscuration alone can hardly reproduce the fraction of log (NH/cm−2) ≥ 24 sources at least at z ≲ 3. This requires an additional torus component with a thickness that decreases with luminosity to match the data. The torus should be present in all evolutionary stages of a visible AGN to be effective, although galaxy-scale gas obscuration may be sufficient to reproduce the obscured fraction with 22 < log (NH/cm−2) < 24 (Compton-thin, CTN) if we assume extremely compact gas disc components. The claimed drop of CTN fractions with increasing luminosity does not appear to be a consequence of AGN feedback, but rather of gas reservoirs becoming more compact with decreasing stellar mass.
black hole physics, galaxies: evolution, galaxies: fundamental parameters, galaxies: structure, galaxies:ãctive, quasars: supermas- sive black holes
1365-2966
10878–10896
Alonso-Tetilla, Alba V.
5af2ce28-2842-4c5a-ab20-ab2a8420ad6c
Shankar, Francesco
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Fontanot, Fabio
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Menci, Nicola
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Valentini, Milena
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Buchner, Johannes
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Laloux, Brivael
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Lapi, Andrea
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Puglisi, Annagrazia
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Alexander, David M.
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Allevato, Viola
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Andonie, Carolina
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Bonoli, Silvia
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Hirschmann, Michaela
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López, Iván E.
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Raimundo, Sandra I.
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Almeida, Cristina Ramos
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Alonso-Tetilla, Alba V.
5af2ce28-2842-4c5a-ab20-ab2a8420ad6c
Shankar, Francesco
b10c91e4-85cd-4394-a18a-d4f049fd9cdb
Fontanot, Fabio
5bea4477-c8fe-4dc6-b0b6-53a8497e58c2
Menci, Nicola
e68473f0-6f7f-48b8-8b76-088d8752df6a
Valentini, Milena
c7d233e5-f075-44ba-ac45-cff3f125b4aa
Buchner, Johannes
e40a3ffc-11c5-44e0-9486-9241cea03f0d
Laloux, Brivael
a8be06b5-4182-4045-b14c-193c33134a9a
Lapi, Andrea
126b5f87-60fa-4a57-8b84-802d5ffb1f17
Puglisi, Annagrazia
97237841-1e6d-48fb-9133-671b6f3af18b
Alexander, David M.
c7e13f1a-f60e-417b-938a-96cd64c50c26
Allevato, Viola
cced4e40-6a45-4261-911a-442d99a6aeb7
Andonie, Carolina
05d3e7e3-65d4-433f-9bdf-c1e1668d713d
Bonoli, Silvia
3b8caa29-7d4b-47a9-8dba-ec67ffcae47a
Hirschmann, Michaela
a3004aff-e242-49d0-890c-aff36446c037
López, Iván E.
b1faa3a5-76ff-4bd0-bbbe-d30d3d4aa1fc
Raimundo, Sandra I.
881da27d-b495-4512-8413-d1f512f1d208
Almeida, Cristina Ramos
407b9f57-0072-415e-826d-7f711fc5fe65

Alonso-Tetilla, Alba V., Shankar, Francesco, Fontanot, Fabio, Menci, Nicola, Valentini, Milena, Buchner, Johannes, Laloux, Brivael, Lapi, Andrea, Puglisi, Annagrazia, Alexander, David M., Allevato, Viola, Andonie, Carolina, Bonoli, Silvia, Hirschmann, Michaela, López, Iván E., Raimundo, Sandra I. and Almeida, Cristina Ramos (2024) Probing the roles of orientation and multi-scale gas distributions in shaping the obscuration of Active Galactic Nuclei through cosmic time. Monthly Notices Of The Royal Astronomical Society, 527 (4), 10878–10896, [stad3265]. (doi:10.1093/mnras/stad3265).

Record type: Article

Abstract

The origin of obscuration in Active Galactic Nuclei (AGN) is still an open debate. In particular, it is unclear what drives the relative contributions to the line-of-sight column densities from galaxy-scale and torus-linked obscuration. The latter source is expected to play a significant role in Unification Models, while the former is thought to be relevant in both Unification and Evolutionary Models. In this work, we make use of a combination of cosmological semi-analytic models and semi-empirical prescriptions for the properties of galaxies and AGN, to study AGN obscuration. We consider a detailed object-by-object modelling of AGN evolution, including different AGN light curves (LCs), gas density profiles, and also AGN feedback-induced gas cavities. Irrespective of our assumptions on specific AGN LC or galaxy gas fractions, we find that, on the strict assumption of an exponential profile for the gas component, galaxy-scale obscuration alone can hardly reproduce the fraction of log (NH/cm−2) ≥ 24 sources at least at z ≲ 3. This requires an additional torus component with a thickness that decreases with luminosity to match the data. The torus should be present in all evolutionary stages of a visible AGN to be effective, although galaxy-scale gas obscuration may be sufficient to reproduce the obscured fraction with 22 < log (NH/cm−2) < 24 (Compton-thin, CTN) if we assume extremely compact gas disc components. The claimed drop of CTN fractions with increasing luminosity does not appear to be a consequence of AGN feedback, but rather of gas reservoirs becoming more compact with decreasing stellar mass.

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Accepted/In Press date: 20 October 2023
e-pub ahead of print date: 25 October 2023
Published date: 1 February 2024
Keywords: black hole physics, galaxies: evolution, galaxies: fundamental parameters, galaxies: structure, galaxies:ãctive, quasars: supermas- sive black holes

Identifiers

Local EPrints ID: 483401
URI: http://eprints.soton.ac.uk/id/eprint/483401
ISSN: 1365-2966
PURE UUID: ba839b6b-877b-4582-9a80-400140316ced
ORCID for Alba V. Alonso-Tetilla: ORCID iD orcid.org/0000-0002-6916-9133

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Date deposited: 30 Oct 2023 17:34
Last modified: 03 Sep 2024 02:03

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Contributors

Author: Fabio Fontanot
Author: Nicola Menci
Author: Milena Valentini
Author: Johannes Buchner
Author: Brivael Laloux
Author: Andrea Lapi
Author: Annagrazia Puglisi
Author: David M. Alexander
Author: Viola Allevato
Author: Carolina Andonie
Author: Silvia Bonoli
Author: Michaela Hirschmann
Author: Iván E. López
Author: Sandra I. Raimundo
Author: Cristina Ramos Almeida

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