Modeling of Modified Electron-acoustic Solitary Waves in a Relativistic Degenerate Plasma

M. R. Hossen,A. A. Mamun 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.12

The modeling of a theoretical and numerical study on the nonlinear propagation of modifiedelectron-acoustic (mEA) solitary waves has been carried out in an unmagnetized, collisionless, relativistic,degenerate quantum plasma (containing non-relativistic degenerate inertial cold electrons,both non-relativistic and ultra-relativistic degenerate hot electron and inertial positron fluids, andpositively-charged static ions). A reductive perturbation technique is used to derive the planar andthe nonplanar Korteweg-de Vries (K-dV) equations, which admit a localized wave solution for thesolitary profile. The solitary wave’s characteristics are found to have been influenced significantlyforin the non-relativistic and the ultra-relativistic limits. The mEA solitary waves are also foundto have been significantly modified due to the effects of the degenerate pressure and the numberdensities of this dense plasma’s constituents. The properties of the planar K-dV solitary wave arequite different from those of the nonplanar K-dV solitary wave. The relevance of our results toastrophysical objects (like white dwarfs and neutron stars), which are of scientific interest, is brieflymentioned.

Study of the Higher-order Shock Excitations in a Degenerate Quantum Plasma

M. A. Hossen,M. R. Hossen,A. A. Mamun 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.11

We propose a comprehensive theory for one dimensional ion-acoustic shock waves (IASWs) in anunmagnetized degenerate quantum plasma that is assumed to contain inertial ions and relativisticdegenerate electrons. The modified Burgers (mB) and the Gardner equations have been derived byemploying the reductive perturbation method and have been analyzed in order to identify the basicfeatures (amplitude, width, speed, etc.) of the IASWs. The basic features of these shocks obtainedfrom this analysis are observed to be significantly different from those obtained from the standardBurgers equation. The implications of our results in space and interstellar compact objects (viz. white dwarfs, non-rotating neutron stars, active galactic nuclei, cometary tails, etc.) are brieflymentioned.

Time-dependent Cylindrical and Spherical Ion-acoustic Solitary Structures in Relativistic Degenerate Multi-ion Plasmas with Positively-charged Heavy Ions

M. R. Hossen,L. Nahar,A. A. Mamun 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.11

The properties of time-dependent cylindrical and spherical, modified ion-acoustic (mIA) solitarystructures in relativistic degenerate multi-ion plasmas (containing degenerate electron fluids, inertialpositively-, as well as negatively-, charged light ions, and positively-charged static heavy ions)have been investigated theoretically. This investigation is valid for both non-relativistic and ultrarelativisticlimits. The well-known reductive perturbation method has been used to derive theKorteweg-de Vries (K-dV) and the mK-dV equations for studying the basic features of solitarywaves. The fundamental characteristics of mIA solitary waves are found to be significantly modifiedby the effects of the degenerate pressures of the electron and the ion fluids, their number densities,and the various charge states of heavy ions. The relevance of our results in astrophysical compactobjects like white dwarfs and neutron stars, which are of scientific interest, is briefly discussed.

Nonplanar Solitons in a Degenerate Multi-species Plasma

M. G. Shah,A. A. Mamun,M. R. Hossen 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.8

The nonlinear propagation of cylindrical and spherical positron-acoustic solitary waves (PASWs) in an unmagnetized, collisionless, relativistic, degenerate plasma system that consists of nonrelativistic inertial cold positrons, relativistic degenerate electron and hot positron fluids, and positively-charged immobile ions has been investigated theoretically. By using a reductive perturbation technique, we derive the Korteweg-de Vries (K-dV) equation. The solitary wave solution has been numerically analyzed to comprehend the localized electrostatic disturbances. We observed that the effects of the degenerate pressure, relativity, and the number densities of inertial cold positrons, hot positrons, electrons, and positively-charged static ions notably modify the fundamental features of the cylindrical and the spherical PASWs. The implications of our results for dense plasmas in astrophysical compact objects (e.g., non-rotating white dwarfs, neutron stars, etc.) are briefly discussed.

Shock Waves and Double Layers in a Quantum Electron-positron-ion Plasma

P. R. Dip,M. A. Hossen,M. Salahuddin,A. A. Mamun 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.4

The ion-acoustic (IA) shock waves and double layers (DLs) in an unmagnetized, dissipative, quantum electron-positron-ion (EPI) plasma (composed of a viscous heavy ion fluid, Fermi electrons and positrons) have been theoretically investigated. The higher-order Burgers and Gardner equations are derived by employing the reductive perturbation method. The basic features of the IA shock waves and the DLs are identified by analyzing the solutions of both the higher-order Burgers and Gardner equations. The ratio of the Fermi temperature of the positron to that of the electron, the Fermi pressure of electrons and positrons, the viscous force, the plasma particle number densities, etc. are found to change remarkably the basic features (viz. amplitude, width, phase speed, etc.) of the IA waves. The results of our investigation may be helpful in understanding the nonlinear features of localized IA waves propagating in quantum EPI plasmas which are ubiquitous in astrophysical, as well as laboratory, environments.

Effects of Bohm Potentials and Fermi Temperatures on Nonplanar Solitary and Shock Excitations in a Strongly-Coupled Quantum Plasma

P. R. Dip,M. A. Hossen,M. Salahuddin,A. A. Mamun 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.70 No.8

An exhaustive theoretical investigation considering nonplanar geometry (cylindrical and spherical) in an unmagnetized, collisionless, strongly-coupled quantum electron-positron-ion (EPI) plasma (composed of viscous, positively-charged inertial heavy ion fluids, Fermi electrons and positrons) has been carried out on the nonlinear propagation of the ion-acoustic (IA) waves. The generalized quantum hydrodynamic model using the reductive perturbation method has been utilized to derive the Korteweg-de Vries (K-dV) and Burgers equations. The basic features (e.g., phase speed, amplitude, and width) of the IA solitary and shock waves are identified by analyzing the stationary solitary and shock wave solutions of the K-dV and Burgers equations, respectively. The basic characteristics of the IA nonlinear structures are found to be significantly modified by the ratio of the Fermi temperatures of positrons to electrons, the Fermi pressures of electrons and positrons, the plasma particle number densities, etc.. The results of this theoretical investigation may be useful in studying the IA waves propagating in both astrophysical and laboratory EPI plasmas (viz. white dwarfs, super-intense laser-dense matter experiments, etc.).

Korteweg-de Vries-Burgers Equation in a Multi-Component Magnetized Plasma with Nuclei of Heavy Elements

B. Hosen,M. Amina,A. A. Mamun,M. R. Hossen 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.12

The nonlinear properties of ion-acoustic (IA) waves are investigated in a relativistically degenerate magnetized quantum plasma, whose constituents are non-degenerate inertial ions, degenerate electrons and immobile positively-charged heavy elements. For nonlinear studies, the well-known reductive perturbation technique is employed to derive the Korteweg-de Vries-Burger equation in the presence of relativistically degenerate electrons. Numerically, the amplitude, width, and phase speed are shown to be associated with the localized IA solitons, and shocks are shown to be significantly influenced by the various intrinsic parameters relevant to our model. The solitary and the shock wave properties have been to be influenced in the non-relativistic, as well as the ultrarelativistic, limits. The effects of the external magnetic field and the obliqueness are found to change the basic properties of IA waves significantly. The present analysis can be useful in understanding the collective process in dense astrophysical environments, like there of non-rotating white dwarfs, neutron stars, etc.