paper

Modeling High-Velocity QSO Absorbers with Photoionized MHD Disk-Winds

arXiv:1009.5644 · doi:10.1088/2041-8205/723/2/L228

Abstract

We extend our modeling of the ionization structure of magnetohydrodynamic (MHD) accretion-disk winds, previously applied to Seyfert galaxies, to a population of quasi-stellar-objects (QSOs) of much lower X-ray-to-UV flux ratios, i.e. smaller index, motivated by UV/X-ray ionized absorbers with extremely high outflow velocities in UV-luminous QSOs. We demonstrate that magnetically-driven winds ionized by a spectrum with can produce the charge states responsible for \civ ~and \fexxv/\fexxvi ~absorption in wind regions with corresponding maximum velocities of (\civ) $\lsim 0.1c$ and $v({\rm \fexxv}) \lsim 0.6 c$ (where is the speed of light) and column densities cm, in general agreement with observations. In contrast to the conventional radiation-driven wind models, {\it high-velocity flows are always present in our MHD-driven winds} but manifest in the absorption spectra only for $α_{\rm ox} \lsim -2$, as larger values ionize the wind completely out to radii too large to demonstrate the presence of these high velocities. We thus predict increasing velocities of these ionized absorbers with decreasing (steeper) , a quantity that emerges as the defining parameter in the kinematics of the AGN UV/X-ray absorbers.

11 pages, Figs.1-3 (color), accepted to ApJL

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