The role of superthermal electrons and positrons on magnetised oscillatory shock waves

Nonlinear ion-acoustic solitary and shock waves were analysed in a system of collisionless, dissipative and magnetised multicomponent plasma. The system was made up of a fluid of inertial ions, electrons that were distributed superthermally and positrons. Korteweg–de Vries–Burgers (KdVB) equation was produced when the reductive perturbation approach was used to evaluate the plasma system nonlinearly. The tanh method was used to find the analytical solution of the derived KdVB equation. The study demonstrated that the superthermal parameters, magnetic field direction, ion kinematic viscosity and positron and electron concentration all affect the oscillatory shock wave features such as speed, amplitude and width. On the other hand, the bifurcation analysis showed that the equilibrium point produces an unstable spiral source as the Burgers term increases and that it transforms into a nodal source with any further increase in the Burgers term. The present results are helpful for understanding collective phenomena and the stability criterion of ion-acoustic (IA) solitary and shock waves in magnetoplasmas with superthermal electrons and positrons, which are observed in some astrophysical environments, like the interstellar medium. (author)