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A study of cosmic ray modified shock structures is presented for a system of four fluids consisting upon cosmic rays, thermal plasmas, forward and backward propagating self-excited Alfvén waves. A fluid model is employed to study the energy exchange mechanisms for the shock formation where cosmic rays, forward and backward propagating Alfvén waves are taken massless fluids in the comparison of thermal plasmas. This work may help to understand theoretical and observational perspective of the processes involved in supernova environment. [ABSTRACT FROM AUTHOR]

The propagation of energetic charged particles and cosmic rays in magnetized thermal plasma is focused. We consider a four-fluid system that consists of thermal plasma, cosmic rays, and two opposite propagating Alfvén waves to investigate the dynamics and energy exchange mechanisms of the system. Additionally, cosmic rays diffusion within the plasma is considered along the magnetic field lines whereas neglected the cross field line diffusion effects. This study is important for understanding of pressure gradients and their impact on the feedback in astrophysical environment. Over the last few decades, this problem becomes important when we discuss the interaction of cosmic rays with plasma in space, such as interstellar clouds or interstellar medium. [ABSTRACT FROM AUTHOR]

Plasma outflow or wind against a gravitational potential under the influence of cosmic rays is studied in the context of hydrodynamics. Cosmic rays interact with the plasma via hydromagnetic fluctuations. In the process, cosmic rays advect and diffuse through the plasma. We adopt a multi-fluid model in which, besides thermal plasma, cosmic rays and self-excited Alfvén waves are also treated as fluids. We seek possible, physically allowable steady-state solutions of three-fluid (one Alfvén wave) and four-fluid (two Alfvén waves) models with given boundary conditions at the base of the potential well. Generally speaking, there are two classes of outflows—subsonic and supersonic (with respect to a suitably defined sound speed). A three-fluid model without cosmic-ray diffusion can be studied in the same way as the classic stellar wind problem, and is taken as a reference model. When cosmic-ray diffusion is included, there are two categories of solutions. One of them resembles the three-fluid model without diffusion, and the other behaves like thermal wind at large distances when the waves wither and cosmic rays are decoupled from the plasma. We also examine the effect of wave damping mechanisms (such as nonlinear Landau damping). Roughly speaking, the effect is much smaller in supersonic outflow than in subsonic outflow. [ABSTRACT FROM AUTHOR]