Fluid model simulation of solitons in an ultra-relativistic electron–positron plasma

Abstract

In this study, the fully nonlinear relativistic ideal two-fluid equations are numerically integrated to show how solitary wave pulses can arise from simple initial conditions when electromagnetic waves parallel to a constant magnetic field are considered in a degenerate electron–positron plasma. The formation and propagation of one-dimensional fast wave solitons and slower wave pulses are identified as being related to a sound mode and the Alfvén mode, respectively. While solitons in relativistic electron–positron and similar plasmas have been studied theoretically by many authors, apart from some particle simulations and stationary large-amplitude treatments, only small-amplitude studies resulting in Korteweg–de Vries and related model equations have been employed to illustrate the occurrence of such nonlinear structures. These results extend and complement earlier theoretical treatments and are especially relevant for astrophysical plasmas.