X-ray Emissions from Three-dimensional Magnetohydrodynamic Coronal Accretion Flows

TL;DR

This study models X-ray emissions from black hole accretion systems using 3D MHD simulations, revealing spectral properties and variability consistent with Seyfert galaxies, and discusses reflection features like iron lines.

Contribution

It introduces a novel combination of 3D MHD simulation data with radiative transfer modeling to analyze X-ray spectra and variability in accretion disk-corona systems.

Findings

Spectra match typical Seyfert galaxy observations.

Rapid X-ray variability linked to magnetorotational instability.

Reflection features, including iron lines, are briefly discussed.

Abstract

We calculate the radiation spectrum and its time variability of the black hole accretion disk-corona system based on the three-dimensional magnetohydrodynamic simulation. In explaining the spectral properties of active galactic nuclei (AGNs), it is often assumed that they consist of a geometrically thin, optically thick disk and hot, optically thin corona surrounding the thin disk. As for a model of the corona, we adopt the simulation data of three-dimensional, non-radiative MHD accretion flows calculated by Kato and coworkers, while for a thin disk we assume a standard type disk. We perform Monte Carlo radiative transfer simulations in the corona, taking into account the Compton scattering of soft photons from the thin disk by hot thermal electrons and coronal irradiation heating of the thin disk, which emits blackbody radiation. By adjusting the density parameter of the MHD coronal flow, we can produce the emergent spectra which are consistent with those of typical Seyfert galaxies. Moreover, we find rapid time variability in X-ray emission spectra, originating from the density fluctuation produced by the magnetorotational instability in the MHD corona. The features of reflection component including iron fluorescent line emission are also briefly discussed.