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2020天文年會
中研院天文所 國際會議廳

論文摘要

From cosmic ray accompanied outflows to quasi-thermal outflows

[ Oral ]

Bilal Ramzan (Institute of Astronomy, National Central University, Zhongli District, Taoyuan City, Taiwan (R.O.C.))D.O. Chernyshov (I.E. Tamm Theoretical Physics Division of P.N. Lebedev Institute of Physics, Leninskii pr. 53, 119991 Moscow, Russia)Chung-Ming Ko (Department of Physics and Center of Complex System, National Central University, Zhongli District., Taoyuan City, Taiwan (R.O.C.))

In the galactic environment thermal plasma, cosmic rays and magnetic field are roughly in equipartition of energy. We are interested in the dynamical role played by cosmic rays on outflows launched from the galactic disk. Our model is a four-fluid system which includes thermal plasma, cosmic rays and two opposite propagating self-excited Alfvèn waves. We seek steady state solutions of the system in flux-tube formulation. There are two categories of physically allowable solutions depending on the boundary conditions: cosmic ray accompanied outflows and quasi-thermal outflows. In the former one, cosmic ray is coupled to plasma all the way to large distances. In the later one, waves die out and cosmic ray is decoupled from the plasma and the outflow behaves like a pure thermal wind at large distances. To extend the model, we add wave damping mechanisms, such as nonlinear Landau damping. As expected, more complicated flow profiles become possible.