Variability and Parameter Dependence of Hard X-Ray Obscuration Around Supermassive Black Holes in Active Galaxies

Abstract

We investigate hard X-ray obscuration of Active Galactic Nuclei (AGNs) by considering photoionization processes for a number of simulated accretion-disk winds in our magnetohydrodynamic (MHD) framework. To follow up our earlier work on calculating synthetic AGN obscuration functions, we are motivated in this work to expand our examination of the dependences of obscuration on individual parameters associated with MHD wind and coronal X-ray such as: X-ray luminosity L ion, photon index Γ, density of the wind n o and its radial gradient p where n ∝ n o r −p . We find that AGN appear to undergo a relatively drastic transition from more obscured state (e.g., N H ≳ 1022 cm−2) to unobscured state (i.e., N H ≲ 1022 cm−2) as p approaches to ∼1.1 in these calculations. In the current formalism, luminosity is linearly coupled to wind density (i.e., L X ∝ n o ), and our calculations also indicate AGN become more obscured at higher luminosity. We further discuss the plausibility of the current model in comparison with observations.