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

ABSTRACT We investigate the X-ray properties of a sample of 71 broad- and narrow-line active galactic nucleus (AGN) at 2z11 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 H 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.