A New Interpretation for the Hot Corona in Active Galactic Nuclei

TL;DR

This paper proposes a new model for the hot corona in active galactic nuclei, where magnetic reconnection layers produce X-ray emission through plasmoid formation and inverse-Compton scattering, aligning well with observations.

Contribution

It introduces a heuristic framework for the magnetic reconnection layer in AGN coronae, linking its geometry and magnetization to X-ray luminosity and observational data.

Findings

Model matches observed X-ray luminosity relations.

Reconnection layer height correlates with X-ray emission.

Good agreement with IRAS 13224-3809 observations.

Abstract

This work attempts to provide a new interpretation for the hot corona in active galactic nuclei (AGNs). A thin parabolic magnetic reconnection layer, anchored at the innermost disk and extending along the boundary of the magnetic tower for a few tens of gravitational radii, serves as a hard-X-ray source above the disk. Within this reconnection layer, the tearing instability leads to the formation of a chain of plasmoids, which contain relativistic electrons that generate X-ray radiation through inverse-Compton (IC) scattering of soft photons emitted by the accretion disk. Based on previous theoretical works and numerical simulations, we develop a heuristic framework to parameterize the geometry and magnetization of the reconnection layer, as well as to compute both the power of the IC-scattering radiation and the height of the reconnection layer. Our model allows for a quantitative investigation of the relation between the height of the corona and the X-ray radiation luminosity, which can be directly compared against the observed relation from X-ray reverberation mapping of individual AGNs. The theoretical results are in good agreement with the observations of IRAS 13224-3809, indicating the validation of our model.