Fully nonlinear heavy ion-acoustic solitary waves in astrophysical degenerate relativistic quantum plasmas

Fully nonlinear features of heavy ion-acoustic solitary waves (HIASWs) have been investigated in an astrophysical degenerate relativistic quantum plasma (ADRQP) containing relativistically degenerate electrons and non-relativistically degenerate light ion species, and non-degenerate heavy ion species. The pseudo-energy balance equation is derived from the fluid dynamical equations by adopting the well-known Sagdeev-potential approach, and the properties of arbitrary amplitude HIASWs are examined. The small amplitude limit for the propagation of HIASWs is also recovered. The basic features (width, amplitude, polarity, critical Mach number, speed, etc.) of HIASWs are found to be significantly modified by the relativistic effect of the electron species, and also by the variation of the number density of electron, light ion, and heavy ion species. The basic properties of HIASWs, that may propagated in some realistic astrophysical plasma systems (e.g., in white dwarfs), are briefly discussed.     

Electromagnetic ion waves in cold relativistic plasmas

The high-energy processes which occur in many astrophysical objects have motivated recent studies (e.g., Tsintsadze and Tsikarishvili, 1976; Ferrariet al., 1978; Sweeney and Stewart, 1978) of large amplitude wave propagation in plasmas. Such investigations are also of interest for laboratory experiments where strong laser radiation interacts with a high-density target. In the present paper we shall show that even rather small amplitude waves in the presence of an external magnetic field can induce particle velocities which are comparable to the velocity of light. In this ultrarelativistic limit we shall demonstrate that two completely new types of circularly polarized waves appear and that under certain conditions, modulational instabilities occur. Finally we look at the possibility to relate the amplitudes and wavelengths of such waves to pulsar data.     

Strong electromagnetic waves in a magnetized relativistic electron-positron plasma

It is shown that in a strongly magnetized relativistic electron-positron plasma, strongly localized large amplitude circularly polarized electromagnetic wave pulses exist. The localization is due to relativistic mass variation as well as ponderomotive force effects. Three types of pulses are found analytically: the sharply spiked pulse in a strongly magnetized cold plasma, the smooth pulse in a week magnetized warm plasma, and the moderately spiked pulse for a weakly magnetized cold plasma. The physical mechanisms giving rise to these pulses are distinct for each case. Possible implications of our investigation to pulsar radiation are discussed.     

Stimulated scattering of electromagnetic waves in dusty plasmas

The nonlinear coupling between a large amplitude electromagnetic wave and the slow background motion in a dusty plasma is considered. Stimulated scattering instabilities are investigated. The relevance of our investigation to cometary and astrophysical plasmas is pointed out.     

Nonlinear low frequency electromagnetic waves in a relativistic electron-positron plasma

Using an exact solution of Maxwell's equations and the relativistic equations of motion for electrons and positrons we demonstrate the existence of an electromagnetic wave with a frequency considerably lower that the electron cyclotron frequency. For such a wave the cutoff frequency is determined by the Langmuir frequency and by the wave amplitude. For realistic pulsar parameters a remarkable reduction in the cutoff frequency is then controlled by nonlinear relativistic effects. Modulation instability of this wave is also investigated both analytically and numerically.     

Propagation of low frequency electromagnetic waves in a relativistic electron gas

In this paper the propagation of low frequency electro-magnetic waves with large amplitudes in a magnetized plasma is discussed. It is shown that penetration of the magnetic-dipole radiation in the medium of the Crag Nebula seems possible     

Modulational behavior of electromagnetic waves in ultra-relativistic electron-positron plasmas

The dynamical properties of electromagnetic (EM) waves in ultra-relativistic electron-positron (EP) plasmas are analytically investigated on the basis of the nonlinear governing equations obtained from a kinetic way. It is shown that the EM wave envelope will collapse and be trapped into a localized region for the modulation interaction with low frequency density variation induced by ponderomotive force. The correlation between the localized strong wave field and the pulsar radio emission is discussed.     

Nonlinear propagation of electromagnetic waves in magnetized electron-positron plasmas

The nonlinear interaction of the external magnetic field-aligned circularly polarized electro-magnetic radiation with a cold electron-positron plasma is considered. A set of nonlinear equations is derived describing the coupling of the radiation with cold electrostatic oscillations. Modulational instabilities and wave localization are discussed.     

Weakly relativistic solitary waves in multicomponent plasmas with electron inertia

Existence of compressive relativistic solitons is established in an arbitrary ξ-direction, inclining at an angle to the direction of the weak magnetic field (ω _pi ≫ω _Bi ) in this plasma compound with ions, relativistic electrons and relativistic electron beams. It is observed that the absolute linear growth of amplitudes of compressive solitons is due to inactive role of the weak magnetic field and the initial streaming speeds of relativistic electrons, electron beams, and Q _b (ion mass to electron beam mass). Besides, the small initial streaming of electrons is found to be responsible to generate relatively high amplitude compressive solitons. The non-relativistic ions in the background plasma, but in absence of electron-beam drift and in presence of weak magnetic field are the causing effect of interest for the smooth growth of soliton amplitudes in this model of plasma.     

A statistical theory of electromagnetic waves in turbulent plasmas

A statistical theory, previously developed for electrostatic waves is extended to the case of electromagnetic waves in the presence of a constant magnetic field. The theory is nonlinear and contains the effects of mode-mode coupling. The extension is not straightforward as assumed previously by many authors and involves calculation of perturbed trajectories in both velocity and configuration space. A diffusion equation is derived for the average particle distribution function, the associated diffusion tensor is calculated and a nonlinear wave dispersion relation is found. All these results contain the usual quasilinear theory as the lowest order approximation.     

Solitary and rogue waves in Fermi-Dirac plasmas: relativistic degeneracy effects

Ion acoustic (IA) solitary and rogue waves are studied in an unmagnetized plasma consisting of non-degenerate warm ions, relativistically degenerate electrons and positrons. By using the reductive perturbation technique, the evolution of IA solitary waves is described by the Korteweg-de Vries (KdV) equation. However, when the frequency of the carrier wave is much smaller than the ion plasma frequency then the KdV equation is also used to study the nonlinear evolution of modulationally unstable modified IA wavepackets through the derivation of nonlinear Schrödinger equation. It is found that the characteristics of the IA solitary and rogue waves are substantially influenced by the intrinsic plasma parameters. The relevance of the present investigation involving IA solitary and rogue waves in astrophysical plasma environments is also highlighted.     

Trapping of electromagnetic waves by nonlinear resonant interactions with ion sound waves

Resonant wave-wave interaction among one ion sound wave and two electro-magnetic waves in an isotropic plasma is studied. The emphasis is on the possibility of trapping the electromagnetic wave. Equations for the three-wave system are derived. One particularly interesting case is that for which the frequency of ion sound wave is much less than the frequency of electromagnetic waves. For this case it is shown that energy exchange takes place only between the two high frequency waves. The ion sound wave does not participate in the energy exchange process but acts as a kind of catalyst for the interaction. Simple solutions are obtained. It is found that the electromagnetic energy is trapped within a certain spatial region. The trapping width is found to depend, among other parameters, on the magnitude of ion sound wave perturbation. Possible application of the theory to topside ionospheric observations of field-aligned propagation is discussed.     

Nonlinearly coupled electromagnetic ion-cyclotron and magnetosonic waves in astrophysical plasmas

A set of three nonlinearly coupled equations governing the interaction between electromagnetic ion-cyclotron and magnetosonic waves is derived. In appropriate limiting cases, the set yields simplified equations. On the other hand, the full set of equations is used to derive a general dispersion relation for the parametric interaction of electromagnetically modulated ion-cyclotron wave packets. An analytical expression for the growth rate of the electromagnetic modulational instability is presented. The relevance of our investigation to non-thermal electromagnetic fluctuations in astrophysical and cometary plasmas is pointed out.     

Wave processes in nonlinear beams during propagation of waves in pulsar plasmas with different magnetic field orientations

The propagation of nonlinear three-dimensional waves in the form of gaussian beams in pulsars is examined. The defining equations for the wave motion of a plasma with high particle velocities, high electrical conductivity, high wave frequency, and high magnetic fields are the standard equations of magnetogas dynamics. Nonlinear, time-dependent equations are derived for relatively small perturbations of the medium and the orders of magnitude of the parameters of motion such that all the terms in the time-dependent equation are of the same order are written down. Various directions of the unperturbed magnetic field and of the wave propagation which may arise during plasma motion in quasars are considered. In a number of cases a closed analytic solution can be constructed for the propagation of axially symmetric gaussian beams. __________ Translated from Astrofizika, Vol. 49, No. 3, pp. 409–417 (August 2006).     

Kinetic equilibrium of nonlinear electromagnetic waves in electron-positron-ion magnetoplasmas

The problem of a one-dimensional, nonlinear, circularly polarized wave in a collisionless plasma is solved for the case in which the group velocity of the localized wave is zero relative to the plasma frame.For an electron-positron plasma the ponderomotive potential is repulsive, and both small and large amplitude waves in the presence of reflected and transmitted particles is discussed.The inclusion of an external magnetic field such that the cyclotron frequency is smaller than the wave frequency does not alter qualitatively the results of the fieldless case, except for the fact that an electrostatic potential is generated.For the case in which the cyclotron frequency is larger than the wave frequency, the resulting potential is attractive, and it is shown that no localized waves can coexist with confined and transmitted particles. If, however, an ionic component is presnt in the electron-positron plasma, such as may be the case in pulsar magnetospheres, localized waves may again be possible.     

Propagation of plane relativistic shock waves in the presence of a magnetic field

In this paper we obtain similarity solutions for the propagation of plane relativistic shock waves in the presence of a transverse magnetic field for the medium, where the nucleon number density obeys a power law of distance from the plane of explosion. The shock surface moves with constant velocity and the total energy of the disturbance is dependent on time. The solutions are applicable only to an isothermal medium or a cold gas.     

Propagation of cylindrical relativistic shock waves in the presence of a magnetic field

In this paper we obtain similarity solutions for the propagation of cylindrical relativistic shock waves in the presence of a constant azimuthal magnetic field or in its absence for the medium, where the nucleon number density is uniform. The shock surface moves with constant velocity and the total energy of the disturbance is dependent on time. The solutions are applicable only to an isothermal medium or a cold gas.