The Dynamical Structure of the Outflows Driven by a Large-scale Magnetic Field

Abstract

A large-scale magnetic field is crucial in launching and collimating jets/outflows. It is found that the magnetic flux can be efficiently transported inward by a fast-moving corona above a thin disk. In this work, we investigate the dynamical structure of the outflows driven by the large-scale magnetic field advected by a hot corona. With the derived large-scale magnetic field, the outflow solution along every field line is obtained by solving a set of magneto-hydrodynamic equations self-consistently with boundary conditions at the upper surface of the corona. We find that the terminal speeds of the outflows driven from the inner region of the disk are ∼0.01–0.1c. The temperatures of the outflows at a large distance from the black hole are still as high as several ten keV. The properties of the magnetic outflows derived in this work are roughly consistent with the fast outflows detected in some luminous quasars and X-ray binaries (XRBs). The total mass-loss rate in the outflows from the corona is about 7%–12% of the mass-accretion rate of the disk. The three-dimensional field geometry, the velocity, temperature, and density of the outflows derived in this work can be used for calculating the emergent spectra and their polarization of the accretion disk/corona/outflow systems. Our results may help understand the features of the observed spectra of XRBs and active galactic nuclei.