Nonlinear positron-acoustic waves in fully relativistic degenerate plasmas

Abstract

The nonlinear positron-acoustic (PA) waves propagating in a fully relativistic electron-positronion (EPI) plasma (containing degenerate electrons and positrons, and immobile heavy ions) have been theoretically investigated. A fully relativistic hydrodynamic model, which is consistent with the relativistic principle has been used, and the reductive perturbation method is employed to derive the dynamical Korteweg-de Vries equation. The dynamics of electrons as well as positrons, and the presence of immobile heavy ions are taken into account. It is found that the effects of relativistic degeneracy of electrons and positrons, static heavy ions, plasma particles velocity, enthalpy, etc have significantly modified the basic properties of the PA solitary waves propagating in the fully relativistic EPI plasmas. The application of the results of our present work in astrophysical compact objects such as white dwarfs and neutron stars, etc are briefly discussed.

Subsonic and supersonic nucleus-acoustic solitary waves in thermally degenerate plasmas with heavy nucleus species

“…• The correctness of the results are verified by obtaining the same results from the analysis of analytical solitary wave solution of the energy integral [defined by (32) with the pseudo-potential V (φ) provided in (34) and (41)] and the direct analysis of the pseudo-potential V (φ) [provided in (34) and ( 41)].…”

“…It is obvious from figures 2−7 that (i) the presence of SHNS supports the existence of small amplitude subsonic NA SWs; (ii) the amplitude (width) of the subsonic NA SWs increases (decreases) with the increase in number density (represented by µ) of the SHNS; (iii) the effects of non-relativistically (γ e = 5/3) and ultrarelativistically (γ e = 4/3) DES are in against the formation of the subsonic NA SWs, and thus, give rise to the formation of the supersonic NA SWs; (iv) the amplitude of the supersonic NA SWs in no-relativistically DES (γ e = 5/3) is much smaller than that in ultrarelativistically DES (γ e = 4/3), but is much larger than that in BDES (γ e = 1); (iv) the width of the supersonic NA SWs in non-relativistically DES (γ e = 5/3) is much wider than that in ultra-relativistically DES (γ e = 4/3); (v) the small amplitude approximation provides almost the same results as the direct analysis of the pseudopotential V (φ) [defined by (34)] does.…”

“…It is usual for almost all non-degenerate and degenerate plasma situations that E eT > Eed, E et , and |φ| < 1 since E eT = Eed + E et , φ = Φ/E eT , and E et k B T e0 . Thus, V (φ) [defined by (34)] can be expanded as…”

“…We now study the basic features of small amplitude NA SWs by considering the approximation V (φ) = C 2 φ 2 + C 3 φ 3 . This approximation along with the condition V (φ m ) = 0 (where φ m ( = 0) is the amplitude of the solitary waves) reduces the SW solution of (32) to We have also reexamined these basic features of these subsonic and supersonic NA SWs by the direct analysis of pseudo-potential V (φ) defined by (34) for the same set of plasma parameters. The results are displayed in figures 5−7.…”

Twisted positron-acoustic wave in quantum plasmas

“…Indeed, the frequency of PAWs is much larger than the ion plasma frequency, and their phase velocity lies between the thermal velocities of cold and hot positrons [11]. The existence of distinct groups of positrons in EPI plasmas has been verified by many authors, and much effort has been dedicated to study the propagation of PAWs in various plasma systems using linear and nonlinear regime [12][13][14][15][16]. In this regard, Bharuthram [17] investigated two types of hot and cold positrons dynamics in pulsar magnetosphere, and Nejoh [18] demonstrated the relation between amplitude of positronacoustic solitary waves and positrons temperature in an electronpositron plasma with an electron beam.…”