Magneto-centrifugal Wind with Applications to Astrophysical Accretion Disks

We calculate the structure of radially self-similar magneto-centrifugal winds with a wide range of magnetic flux distribution, mass loading, and injection speed at the base of the wind. A variety of wind structures is obtained, including winds driven by magneto-centrifugal and magnetic pressure gradient forces. The critical magnetic tilt needed to achieve an Alfven transition is sensitive to the wind properties, especially the magnetic flux distribution and injection speed, and generally exceeds the 30 degrees minimum for a magneto-centrifugal slingshot. A connection between magnetic tilt and minimization of the specific wind energy is conjectured. The least tilted wind solution is shown to approach the potential solution at low mass loading. Gaseous disks in star-forming galaxies and active galactic nuclei may contain dynamically important magnetic fields and significant flux of cosmic rays. In contrast with radiation-pressure dominated disks, a much weaker energy input in cosmic rays is required to support the disk against vertical gravity, and to drive a magneto-centrifugal outflow. Taking into account cosmic ray ionization, streaming, injection from massive stars and energy losses, we calculate the transition from a hydrostatic disk to an outflowing wind. The solutions are constrained by the slow-magnetosonic critical point associated with cosmic ray streaming; the wind is initially driven by the cosmic ray pressure gradient rather than the magneto-centrifugal force, with the magneto-centrifugal force dominating at larger heights above the disk. The specific example that is explored in quantitative detail involves a near Eddington accretion flow onto a supermassive black hole, at a distance from the hole where a viscous disk tends to be gravitationally unstable. We find that the disk magnetization is around unity, which optimally fixes the fraction of the radial mass flow returned to the wind at order 0.01. Radial scalings in a constant Q disk are worked out.

Department dc:contributor.department

Astronomy and Astrophysics

Year dc:date.issued

2022

Author dc:creator

• Jing, Shenglin

Advisor dc:contributor.advisor

• Thompson, Christopher

• Accretion Disk
• Active Galactic Nuclei
• Cosmic Ray
• Magneto-centrifugal Wind
• MHD
• Starburst Galaxy

Handle dc:identifier.uri

http://hdl.handle.net/1807/110802

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/110802