A simple model for the X-ray weakness of James Webb Space Telescope-selected broad-line active galactic nuclei (AGNs) is proposed under the assumption that the majority of these sources are fed at super-Eddington accretion rates. In these conditions, the hot inner corona above the geometrically thin disk that is responsible for the emission of X-rays in “normal” AGNs will be embedded instead in a funnel-like reflection geometry. The coronal plasma will Compton upscatter optical/UV photons from the underlying thick disk as well as the surrounding funnel walls, and the high soft-photon energy density will cool down the plasma to temperatures in the range 30-40 keV. The resulting X-ray spectra are predicted to be extremely soft, with power-law photon indices Γ ≃ 2.8-4.0, making high-z super-Eddington AGNs largely undetectable by Chandra.

X-Ray Weak Active Galactic Nuclei from Super-Eddington Accretion onto Infant Black Holes

Haardt F.
2024-01-01

Abstract

A simple model for the X-ray weakness of James Webb Space Telescope-selected broad-line active galactic nuclei (AGNs) is proposed under the assumption that the majority of these sources are fed at super-Eddington accretion rates. In these conditions, the hot inner corona above the geometrically thin disk that is responsible for the emission of X-rays in “normal” AGNs will be embedded instead in a funnel-like reflection geometry. The coronal plasma will Compton upscatter optical/UV photons from the underlying thick disk as well as the surrounding funnel walls, and the high soft-photon energy density will cool down the plasma to temperatures in the range 30-40 keV. The resulting X-ray spectra are predicted to be extremely soft, with power-law photon indices Γ ≃ 2.8-4.0, making high-z super-Eddington AGNs largely undetectable by Chandra.
2024
Madau, P.; Haardt, F.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11383/2189635
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