JWST-discovered AGN: evidence for heavy obscuration in the type-2 sample from the first stacked X-ray detection

Fuente: arXiv
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Autores principales: Comastri, Andrea, Lanzuisi, Giorgio, Vito, Fabio, Marchesi, Stefano, Brusa, Marcella, Gilli, Roberto, Juodzbalis, Ignas, Maiolino, Roberto, Mazzolari, Giovanni, Risaliti, Guido, Scholtz, Jan, Vignali, Cristian
Formato: Preprint
Publicado: 2025
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author Comastri, Andrea
Lanzuisi, Giorgio
Vito, Fabio
Marchesi, Stefano
Brusa, Marcella
Gilli, Roberto
Juodzbalis, Ignas
Maiolino, Roberto
Mazzolari, Giovanni
Risaliti, Guido
Scholtz, Jan
Vignali, Cristian
author_facet Comastri, Andrea
Lanzuisi, Giorgio
Vito, Fabio
Marchesi, Stefano
Brusa, Marcella
Gilli, Roberto
Juodzbalis, Ignas
Maiolino, Roberto
Mazzolari, Giovanni
Risaliti, Guido
Scholtz, Jan
Vignali, Cristian
contents One of the most puzzling properties of the high-redshift AGN population recently discovered by JWST, including both broad-line and narrow-line sources, is their X-ray weakness. With very few exceptions, and regardless of the optical classification, they are undetected at the limits of the deepest Chandra fields, even when stacking signals from tens of sources in standard observed-frame energy intervals (soft, hard, and full bands). It has been proposed that their elusive nature in the X-ray band is due to heavy absorption by dust-free gas or intrinsic weakness, possibly due to high, super-Eddington accretion. In this work, we perform X-ray stacking in three customized rest-frame energy ranges (1-4, 4-7.25, and 10-30 keV) of a sample of 50 Type 1 and 38 Type 2 AGN identified by JWST in the CDFS and CDFN fields. For the Type 2 sub-sample, we reach a total of about 210 Ms exposure, and we report a significant ($\sim 3σ$) detection in the hardest (10-30 keV rest frame) band, along with relatively tight upper limits in the rest frame softer energy bands. The most straightforward interpretation is in terms of heavy obscuration due to gas column densities well within the Compton thick regime ($> 2 \times 10^{24} $cm$^{-2}$) with a large covering factor, approaching 4$π$. The same procedure applied to the Type 1 sub-sample returns no evidence for a significant signal in about 140 Ms stacked data in any of the adopted bands, confirming their surprisingly elusive nature in the X-ray band obtained with previous stacking experiments. A brief comparison with the current observations and the implications for the evolution of AGN are discussed.
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institution arXiv
publishDate 2025
record_format arxiv
spellingShingle JWST-discovered AGN: evidence for heavy obscuration in the type-2 sample from the first stacked X-ray detection
Comastri, Andrea
Lanzuisi, Giorgio
Vito, Fabio
Marchesi, Stefano
Brusa, Marcella
Gilli, Roberto
Juodzbalis, Ignas
Maiolino, Roberto
Mazzolari, Giovanni
Risaliti, Guido
Scholtz, Jan
Vignali, Cristian
Astrophysics of Galaxies
High Energy Astrophysical Phenomena
One of the most puzzling properties of the high-redshift AGN population recently discovered by JWST, including both broad-line and narrow-line sources, is their X-ray weakness. With very few exceptions, and regardless of the optical classification, they are undetected at the limits of the deepest Chandra fields, even when stacking signals from tens of sources in standard observed-frame energy intervals (soft, hard, and full bands). It has been proposed that their elusive nature in the X-ray band is due to heavy absorption by dust-free gas or intrinsic weakness, possibly due to high, super-Eddington accretion. In this work, we perform X-ray stacking in three customized rest-frame energy ranges (1-4, 4-7.25, and 10-30 keV) of a sample of 50 Type 1 and 38 Type 2 AGN identified by JWST in the CDFS and CDFN fields. For the Type 2 sub-sample, we reach a total of about 210 Ms exposure, and we report a significant ($\sim 3σ$) detection in the hardest (10-30 keV rest frame) band, along with relatively tight upper limits in the rest frame softer energy bands. The most straightforward interpretation is in terms of heavy obscuration due to gas column densities well within the Compton thick regime ($> 2 \times 10^{24} $cm$^{-2}$) with a large covering factor, approaching 4$π$. The same procedure applied to the Type 1 sub-sample returns no evidence for a significant signal in about 140 Ms stacked data in any of the adopted bands, confirming their surprisingly elusive nature in the X-ray band obtained with previous stacking experiments. A brief comparison with the current observations and the implications for the evolution of AGN are discussed.
title JWST-discovered AGN: evidence for heavy obscuration in the type-2 sample from the first stacked X-ray detection
topic Astrophysics of Galaxies
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2510.00112