عنوان	Transverse instability of electron-acoustic solitons in a relativistic degenerate astrophysical magnetoplasma
نوع پژوهش	مقاله چاپ شده
کلیدواژه‌ها	relativistic plasma, electron-acoustic wave, soliton, transverse instability, Zakharov-Kuznetsov equations, degenerate fluids
چکیده	Westudy the nonlinear theory of small-amplitude electron-acoustic solitons (EASs) in a relativistic astrophysical magnetoplasma consisting of two-temperature electrons: a sparse population of relativistic nondegenerate classical electrons and a group of fully degenerate dense relativistic electrons (main constituent) immersed in a static magnetic field with a neutralizing stationary ion background. By using the multiple-scale reductive perturbation technique with the Lorentz transformation, the Zakharov-Kuznetsov (ZK) and the modified Zakharov-Kuznetsov (mZK) equations are derived to describe the evolution of EASs in two different regimes of relativistic degeneracy: rd0<50 and rd050,where rd0 (nd0 ncr ) = 1 3 is the degeneracy parameter inwhich nd0 is the unperturbed number density of degenerate electrons and ncr≈6×1029 cm−3 the critical number density at which pF=mec and which defines the emergence of the relativistic regime. Here, pF is the Fermi momentum, me is the invariant electron mass, and c is the speed of light in vacuum. The characteristics of the plane soliton solutions of ZK andmZKequations and the soliton energy are studied.Weshow that the solitons moving at an angle α to the external magnetic field can be unstable under transverse longwavelength perturbations. The growth rates of instabilities are obtained and analyzed with the effects of the relativity parameter βcl=kBTcl/mec2 and the degeneracy parameter rd0, where kB is the Boltzmann constant and Tcl is the temperature of classical electrons. Interestingly, the ZK solitons, even if it is stable for the first-order perturbations, can be unstable in the second-order correction. Furthermore, while the first-order growth rates of perturbations for ZK solitons tend to vanish as α→38°, that for themZKsoliton goes to zero asα→90°. However, depending on the angle α, the growth rates are found to be reduced either by increasing the values of βcl or by decreasing the values of rd0. The applications of our results to astrophysical plasmas, such as those in the environments of white dwarfs are discussed.
پژوهشگران	علیرضا عبدی کیان (نفر دوم)، عمر میسرا (نفر اول)