Magnetically-Driven Accretion-Disk Winds and Ultra-Fast Outflows in PG1211+143
Abstract
We present a study of X-ray ionization of magnetohydrodynamic (MHD) accretion-disk winds in an effort to constrain the physics underlying the highly-ionized ultra-fast outflows (UFOs) inferred by X-ray absorbers often detected in various sub-classes of Seyfert active galactic nuclei (AGNs). Our primary focus is to show that magnetically-driven outflows are indeed physically plausible candidates for the observed outflows accounting for the AGN absorption properties of the present X-ray spectroscopic observations. Employing a stratified MHD wind launched across the entire AGN accretion disk, we calculate its X-ray ionization and the ensuing X-ray absorption line spectra. Assuming an appropriate ionizing AGN spectrum, we apply our MHD winds to model the absorption features in an XMM-Newton/EPIC spectrum of the narrow-line Seyfert, . We find, through identifying the detected features with Fe Kα transitions, that the absorber has a characteristic ionization parameter of (c [erg~cm~s-1]) 5-6 and a column density on the order of NH 1023 cm-2, outflowing at a characteristic velocity of vc/c 0.1-0.2 (where c is the speed of light). The best-fit model favors its radial location at rc 200 Ro (Ro is the black hole innermost stable circular orbit), with an inner wind truncation radius at R t 30 Ro. The overall K-shell feature in the data is suggested to be dominated by \ with very little contribution from \ and weakly-ionized iron, which is in a good agreement with a series of earlier analysis of the UFOs in various AGNs including .