TY - JOUR
T1 - JADES – the Rosetta stone of JWST-discovered AGN: deciphering the intriguing nature of early AGN
AU - Juodžbalis, Ignas
AU - Ji, Xihan
AU - Maiolino, Roberto
AU - D’Eugenio, Francesco
AU - Scholtz, Jan
AU - Risaliti, Guido
AU - Fabian, Andrew C
AU - Mazzolari, Giovanni
AU - Gilli, Roberto
AU - Prandoni, Isabella
AU - Arribas, Santiago
AU - Bunker, Andrew J
AU - Carniani, Stefano
AU - Charlot, Stéphane
AU - Curtis-Lake, Emma
AU - de Graaff, Anna
AU - Hainline, Kevin
AU - Parlanti, Eleonora
AU - Perna, Michele
AU - Pérez-González, Pablo G
AU - Robertson, Brant
AU - Tacchella, Sandro
AU - Übler, Hannah
AU - Williams, Christina C
AU - Willott, Chris
AU - Witstok, Joris
N1 - © 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/).
PY - 2024/10/16
Y1 - 2024/10/16
N2 - JWST has discovered a large population of active galactic nuclei (AGN) at high redshift, which are weak in the X-rays. Here we present the NIRSpec spectrum of the most extreme of these objects, GN-28074, an AGN at z=2.26 with prominent hydrogen and He i broad lines, and with the highest limit on the bolometric to X-ray luminosity ratio among all spectroscopically confirmed AGN in GOODS. This source is also characterized by a mid-IR excess, likely associated with the AGN torus’ hot dust. The high bolometric luminosity and moderate redshift of this AGN allow us to explore its properties more in depth relative to other JWST-discovered AGN. The NIRSpec spectrum reveals prominent, slightly blueshifted absorption of H\alpha, H\beta, and He i \lambda10830. The Balmer absorption lines require gas with densities of n\rm H\0^8~\rm cm^-3, consistent with clouds in the broad-line region (BLR). This finding suggests that part of the X-ray weakness is due to high (Compton-thick) X-ray absorption by clouds in the BLR, or in its outer regions. GN-28074 is also extremely radio-weak. The radio weakness can also be explained in terms of absorption, as the inferred density of the BLR clouds makes them attenuate the radio emission through free–free absorption. Alternatively, the nuclear magnetic field may be underdeveloped, resulting both in intrinsically weak radio emission and lack of hot corona, hence intrinsic X-ray weakness. Finally, we show that recently proposed scenarios, invoking hyper-dense outflows or Raman scattering to explain the broad H\alpha, are ruled out.
AB - JWST has discovered a large population of active galactic nuclei (AGN) at high redshift, which are weak in the X-rays. Here we present the NIRSpec spectrum of the most extreme of these objects, GN-28074, an AGN at z=2.26 with prominent hydrogen and He i broad lines, and with the highest limit on the bolometric to X-ray luminosity ratio among all spectroscopically confirmed AGN in GOODS. This source is also characterized by a mid-IR excess, likely associated with the AGN torus’ hot dust. The high bolometric luminosity and moderate redshift of this AGN allow us to explore its properties more in depth relative to other JWST-discovered AGN. The NIRSpec spectrum reveals prominent, slightly blueshifted absorption of H\alpha, H\beta, and He i \lambda10830. The Balmer absorption lines require gas with densities of n\rm H\0^8~\rm cm^-3, consistent with clouds in the broad-line region (BLR). This finding suggests that part of the X-ray weakness is due to high (Compton-thick) X-ray absorption by clouds in the BLR, or in its outer regions. GN-28074 is also extremely radio-weak. The radio weakness can also be explained in terms of absorption, as the inferred density of the BLR clouds makes them attenuate the radio emission through free–free absorption. Alternatively, the nuclear magnetic field may be underdeveloped, resulting both in intrinsically weak radio emission and lack of hot corona, hence intrinsic X-ray weakness. Finally, we show that recently proposed scenarios, invoking hyper-dense outflows or Raman scattering to explain the broad H\alpha, are ruled out.
U2 - 10.1093/mnras/stae2367
DO - 10.1093/mnras/stae2367
M3 - Article
SN - 0035-8711
VL - 535
SP - 853
EP - 873
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -