We investigate the X-ray properties of a sample of 71 broad- and narrow-line active galactic nucleus (AGN) at 2<11 discovered by JWST in the GOODS (Great Observatory Origins Deep Survey) fields, which have the deepest Chandra observations ever obtained. Despite the widespread presence of AGN signatures in their rest-optical and -ultraviolet spectra, the vast majority of them is X-ray undetected. The stacked X-ray data of the non-detected sources also results in a non-detection. The upper limit on the X-ray emission for many of these AGN is one or even two orders of magnitude lower than expected from a standard AGN Spectral Energy Distribution (SED). X-ray absorption by clouds with large (Compton-thick) column density and low dust content, such as the broad-line region (BLR) clouds, can explain the X-ray weakness. In this scenario, the BLR covering factor should be much larger than in low-z AGN or luminous quasars; this is supported by the larger equivalent width of the broad component of Hα in JWST-selected AGN. We also find that the JWST-discovered AGN lack prominent, fast outflows, suggesting that, in JWST-selected AGN, dense gas lingers in the nuclear region, resulting in large covering factors. We also note that a large fraction of JWST-selected AGN matches the definition of narrow-line Seyfert 1, typically accreting at high rates and characterized by a steep X-ray spectrum – this can further contribute to their observed weakness at high-z. Finally, we discuss that the broad Balmer lines used to identify type 1 AGN cannot be ascribed to very massive stars or supernovae, although we show that some of the faintest broad lines could potentially be associated with superluminous SNe.

JWST meets Chandra: a large population of Compton thick, feedback-free, and intrinsically X-ray weak AGN, with a sprinkle of SNe

Trefoloni B.;Carniani S.;Venturi G.
2025

Abstract

We investigate the X-ray properties of a sample of 71 broad- and narrow-line active galactic nucleus (AGN) at 2<11 discovered by JWST in the GOODS (Great Observatory Origins Deep Survey) fields, which have the deepest Chandra observations ever obtained. Despite the widespread presence of AGN signatures in their rest-optical and -ultraviolet spectra, the vast majority of them is X-ray undetected. The stacked X-ray data of the non-detected sources also results in a non-detection. The upper limit on the X-ray emission for many of these AGN is one or even two orders of magnitude lower than expected from a standard AGN Spectral Energy Distribution (SED). X-ray absorption by clouds with large (Compton-thick) column density and low dust content, such as the broad-line region (BLR) clouds, can explain the X-ray weakness. In this scenario, the BLR covering factor should be much larger than in low-z AGN or luminous quasars; this is supported by the larger equivalent width of the broad component of Hα in JWST-selected AGN. We also find that the JWST-discovered AGN lack prominent, fast outflows, suggesting that, in JWST-selected AGN, dense gas lingers in the nuclear region, resulting in large covering factors. We also note that a large fraction of JWST-selected AGN matches the definition of narrow-line Seyfert 1, typically accreting at high rates and characterized by a steep X-ray spectrum – this can further contribute to their observed weakness at high-z. Finally, we discuss that the broad Balmer lines used to identify type 1 AGN cannot be ascribed to very massive stars or supernovae, although we show that some of the faintest broad lines could potentially be associated with superluminous SNe.
2025
Settore PHYS-05/A - Astrofisica, cosmologia e scienza dello spazio
galaxies: high-redshift; galaxies: nuclei; infrared: galaxies; quasars: supermassive black holes; X-rays: galaxies
   Star formation quenching and feedback in galaxies throughout the cosmic epochs
   QUENCH
   European Commission
   Horizon 2020 Framework Programme
   695671

   Super-Eddington Accretion: Wind, Inflow, and Disk
   SEAWIND
   MUR
   PRIN 2022
   F53D23001250006
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/152526
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