Observational Properties of AGN Obscuration During the Peak of Accretion Growth

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Main Authors: Vijarnwannaluk, Bovornpratch, Akiyama, Masayuki, Schramm, Malte, Ueda, Yoshihiro, Matsuoka, Yoshiki, Toba, Yoshiki, Matsumoto, Naoki, Ruiz, Angel, Georgantopoulos, Ioannis, Pouliasis, Ektoras, Koulouridis, Elias, Ichikawa, Kohei, Sawicki, Marcin, Gwyn, Stephen
Format: Preprint
Published: 2024
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author Vijarnwannaluk, Bovornpratch
Akiyama, Masayuki
Schramm, Malte
Ueda, Yoshihiro
Matsuoka, Yoshiki
Toba, Yoshiki
Matsumoto, Naoki
Ruiz, Angel
Georgantopoulos, Ioannis
Pouliasis, Ektoras
Koulouridis, Elias
Ichikawa, Kohei
Sawicki, Marcin
Gwyn, Stephen
author_facet Vijarnwannaluk, Bovornpratch
Akiyama, Masayuki
Schramm, Malte
Ueda, Yoshihiro
Matsuoka, Yoshiki
Toba, Yoshiki
Matsumoto, Naoki
Ruiz, Angel
Georgantopoulos, Ioannis
Pouliasis, Ektoras
Koulouridis, Elias
Ichikawa, Kohei
Sawicki, Marcin
Gwyn, Stephen
contents We investigated the gas obscuration and host galaxy properties of active galactic nuclei (AGN) during the peak of cosmic accretion growth of supermassive black holes (SMBHs) at redshift 0.8-1.8 using X-ray detected AGN with mid-infrared and far-infrared detection. The sample was classified as type-1 and type-2 AGN using optical spectral and morphological classification while the host galaxy properties were estimated with multiwavelength SED fitting. For type-1 AGN, the black hole mass was determined from MgII emission lines while the black hole mass of type-2 AGN was inferred from the host galaxy's stellar mass. Based on the derived parameters, the distribution of the sample in the absorption hydrogen column density ($N_{\rm H}$) vs. Eddington ratio diagram is examined. Among the type-2 AGN, $28\pm5$\% are in the forbidden zone, where the obscuration by dust torus cannot be maintained due to radiation pressure on dusty material. The fraction is higher than that observed in the local universe from the BAT AGN Spectroscopic Survey (BASS) data release 2 ($11\pm3$\%). The higher fraction implies that the obscuration of the majority of AGN is consistent with the radiation pressure regulated unified model but with an increased incidence of interstellar matter (ISM) obscured AGN. We discuss the possibility of dust-free absorption in type-1 AGN and heavy ISM absorption in type-2 AGN. We also find no statistical difference in the star-formation activity between type-1 and type-2 AGN which may suggest that obscuration triggered by a gas-rich merging is not common among X-ray detected AGN in this epoch.
format Preprint
id arxiv_https___arxiv_org_abs_2403_06409
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Observational Properties of AGN Obscuration During the Peak of Accretion Growth
Vijarnwannaluk, Bovornpratch
Akiyama, Masayuki
Schramm, Malte
Ueda, Yoshihiro
Matsuoka, Yoshiki
Toba, Yoshiki
Matsumoto, Naoki
Ruiz, Angel
Georgantopoulos, Ioannis
Pouliasis, Ektoras
Koulouridis, Elias
Ichikawa, Kohei
Sawicki, Marcin
Gwyn, Stephen
Astrophysics of Galaxies
We investigated the gas obscuration and host galaxy properties of active galactic nuclei (AGN) during the peak of cosmic accretion growth of supermassive black holes (SMBHs) at redshift 0.8-1.8 using X-ray detected AGN with mid-infrared and far-infrared detection. The sample was classified as type-1 and type-2 AGN using optical spectral and morphological classification while the host galaxy properties were estimated with multiwavelength SED fitting. For type-1 AGN, the black hole mass was determined from MgII emission lines while the black hole mass of type-2 AGN was inferred from the host galaxy's stellar mass. Based on the derived parameters, the distribution of the sample in the absorption hydrogen column density ($N_{\rm H}$) vs. Eddington ratio diagram is examined. Among the type-2 AGN, $28\pm5$\% are in the forbidden zone, where the obscuration by dust torus cannot be maintained due to radiation pressure on dusty material. The fraction is higher than that observed in the local universe from the BAT AGN Spectroscopic Survey (BASS) data release 2 ($11\pm3$\%). The higher fraction implies that the obscuration of the majority of AGN is consistent with the radiation pressure regulated unified model but with an increased incidence of interstellar matter (ISM) obscured AGN. We discuss the possibility of dust-free absorption in type-1 AGN and heavy ISM absorption in type-2 AGN. We also find no statistical difference in the star-formation activity between type-1 and type-2 AGN which may suggest that obscuration triggered by a gas-rich merging is not common among X-ray detected AGN in this epoch.
title Observational Properties of AGN Obscuration During the Peak of Accretion Growth
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2403.06409