Nonlinear rarefactive isothermal ion acoustic waves in magnetized ultrarelativistic degenerate plasmas

examined in a magnetized ultrarelativistic degenerate plasma, containing warm fluid ions
and ultrarelativistic degenerate inertialess electrons as well as positrons and immobile
heavy negative ions. In the linear regime, the excitation of an isothermal ion-acoustic mode
and its evolution are investigated. The physical behavior of nonlinear rarefactive isothermal
ion-acoustic waves (RIIAWs) in this plasma model is governed by a Zakharov–Kuznetso