Two-dimensional electrostatic solitary waves in magnetized ultradense relativistic quantum electronegative plasmas

The relativistic quantum hydrodynamic formalism is used to study the propagation properties of a two-dimensional ion-acoustic wavepacket in a magnetized quantum plasma environments such as neutron stars, radio pulsars and magnetars. The plasma is consisting of two non-degenerate ion populations of opposite charge sign (positive and negative) and degenerate electrons. Based on the two-dimensional version of the reductive perturbation technique, a Zakharov-Kuznetsov (ZK) equation has been derived and explicit stationary solutions in the form of a localized electrostatic potential pulse has been obtained. The associated bipolar waveform obtained for the electric field is compatible with space and laboratory observations. The influence of various plasma configuration parameters, such as the degeneracy parameter, the magnetic field strength and the negative-ion-to-electron density ratio on electrostatic solitary wave characteristics (speed, amplitude and width) has been examined. The stability of the pulse soliton solution of the ZK equation has been investigated and it was found to be unstable to oblique perturbations. Furthermore, the dependence of the instability growth rate on plasma composition parameters has been discussed. Our results will be useful in understanding the dynamics of nonlinear excitations in dense astrophysical plasma environments, e.g. in white dwarfs and in neutron stars, where a magnetized multi-ion plasma state may occur.