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Paper: Stratified Quasar Winds: Integrating X-ray and Infrared Views of Broad Absorption-line Quasars
Volume: 373, The Central Engine of Active Galactic Nuclei
Page: 305
Authors: Gallagher, S.C.; Everett, J.E.
Abstract: Quasars are notable for the luminous power they emit across decades in frequency from the far-infrared through hard X-rays; emission at different frequencies emerges from physical scales ranging from AUs to parsecs. Each wavelength regime thus offers a different line-of-sight into the central engine and a separate probe of outflowing material. Therefore, obtaining a complete accounting of the physical characteristics and kinetic power of quasar winds requires a panchromatic approach. X-ray and infrared studies are particularly powerful for covering the range of interesting physical scales and ionization states of the outflow. We present a stratified wind picture based on a synthesis of multiwavelength research programs designed to constrain the nature of mass ejection from radio-quiet quasars. This wind comprises three zones: the highly ionzed shielding gas, the ultraviolet broad absorption-line wind, and the cold dusty outflow. The primary launching mechanism for the wind likely varies in each zone. While radiative acceleration on resonance lines dominates for the ultraviolet absorbing wind, the shielding gas may instead be driven by magnetic forces. Ultraviolet continuum radiative pressure, perhaps coupled with magnetic launching, accelerates a dusty outflow that obscures the inner broad-line region in unification schemes.
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