Nucleus-acoustic Waves Research Articles

A theoretical study of heavy nucleus-acoustic waves in white dwarf core environments

A theoretical study of heavy nucleus-acoustic waves in white dwarf core environments

Nonlinear coherent structures of nucleus-acoustic wave excitations in multi-nuclei quantum plasmas with ultra-relativistically degenerate electrons and positrons

The propagation dynamics of the nucleus-acoustic waves (NAW) in a quantum plasma composed of nondegenerate inertial light nuclei, stationary heavy nuclei, and ultra-relativistically degenerate electrons and positrons has been theoretically investigated within the framework of the Boussinesq equation, which is valid for a bi-directional propagation of a small but finite amplitude limit. The N-soliton solution of the Boussinesq equation is derived using Hirota's method. It is found that positive potential structures exist in the sonic and supersonic regimes, whereas negative potential structures are found to be present in the subsonic regime. Pertinent plasma properties are analyzed for one-, two-, and three-soliton solutions in terms of different parameters. In addition to the typical solitary wave solutions, our findings indicate that the nonlinear NAW has breather structures. The three- and four-soliton solutions are used to construct the elastic interaction solutions of the breather–soliton and breather–breather, respectively. The findings are discussed in the context of ultra-relativistic astrophysical plasmas.

Modal stability of low-frequency nucleus-acoustic waves in completely degenerate white dwarf cores and their nearly degenerate surroundings

Modal stability of low-frequency nucleus-acoustic waves in completely degenerate white dwarf cores and their nearly degenerate surroundings

Cylindrical and Spherical Nucleus-Acoustic Solitary and Shock Waves in Degenerate Electron-Nucleus Plasmas

The basic characteristics of cylindrical as well as spherical solitary and shock waves in degenerate electron-nucleus plasmas are theoretically investigated. The electron species is assumed to be cold, ultra-relativistically degenerate, negatively charged gas, whereas the nucleus species is considered a cold, non-degenerate, positively charged, viscous fluid. The reductive perturbation technique is utilized in order to reduce the basic equations (governing the degenerate electron-nucleus plasmas under consideration) to the modified Korteweg-de Vries and Burgers equations. The latter are numerically solved and analyzed to detect the basic characteristics of solitary and shock waves in such electron-nucleus plasmas. The nonlinear nucleus-acoustic waves are found to be propagated in the form of solitary as well as shock waves in such degenerate electron-nucleus plasmas. Their basic properties as well as their time evolution are significantly modified by the effects of cylindrical as well as spherical geometries. The results of this study is expected to be applicable not only to astrophysical compact objects, but also to ultra-cold dense plasmas produced in laboratory.

Propagatory dynamics of nucleus-acoustic waves excited in gyrogravitating degenerate quantum plasmas electrostatically confined in curved geometry

A theoretic model to investigate the dynamics of the longitudinal nucleus-acoustic waves (NAWs) in gyrogravitating electrostatically confined degenerate quantum plasma (DQP) system in spherically symmetric geometry is constructed. The model setup consists of non-degenerate heavy nuclear species (HNS), lighter nuclear species (LNS), and quantum degenerate electronic species (DES). It specifically considers the influences of the Bohm potential, Coriolis rotation, viscoelasticity, and electrostatic confinement pressure (ECP, scaling quadratically in density). A standard normal spherical mode analysis gives a generalized dispersion relation (septic). It highlights the dependency of various atypical instability response on the equilibrium plasma parameters. A numerical illustrative platform portrays that the relative nuclear charge-to-mass coupling parameter (beta) acts as a destabilizing agency and the heavy-to-light nuclear charge density ratio (mu) acts as a stabilizing agency in both the non-relativistic (NR) and ultra-relativistic (UR) limits. Another interesting conjuncture is that the Coriolis rotation introduces a destabilizing influence on the system in both the limits. The progressive analysis presented herein has correlations and consistencies in the dynamic growth backdrop of various compact astro objects and their circumvent atmospheres, such as white dwarfs, neutron stars, etc.

Phase plane analysis and integrability via Bäcklund transformation of nucleus-acoustic waves in white dwarf

Phase plane analysis of nucleus-acoustic waves (NAWs) is explored for the Burgers equation in a white dwarf plasma system constituting degenerate electrons, heavy nuclear species and degenerate light nuclear species. Employing the reductive perturbation method (RPM), the Burgers equation is formulated. The Bäcklund transformation of the Burgers equation is deduced in polynomial form by exploiting the homogeneous balance principle (HBP) which eventually characterizes the integrability of the system in the sense of HBP. Exact solutions are also deduced from the Bäcklund transformation. The phase plane of the planar Hamiltonian system (PHS) is studied and the effects of physical parameters, such as, viscosity (η), total charge number density of lighter to heavier nucleus (μh) and velocity of NAWs (v) are studied on the snoidal, kink and anti-kink NAW solutions of the Burgers equation. The outcomes of this work can be significant in discerning nucleus-acoustic snoidal, kink and anti-kink wave features in white dwarf.

Planar and non-planar nucleus-acoustic solitary waves in warm degenerate multi-nucleus plasmas

A warm degenerate plasma (containing ultra-relativistically or non-relativistically warm degenerate inertia-less electron species, non-relativistically warm degenerate inertial light nucleus species and stationary heavy nucleus species) is considered. The basic features of planar and non-planar solitary structures associated with the degenerate pressure-driven nucleus-acoustic waves propagating in such a warm degenerate plasma system are investigated. The reductive perturbation method, which is valid for small- but finite-amplitude solitary waves, is used. It is found that the effects of non-planar cylindrical and spherical geometries, non- and ultra-relativistically degenerate electron species and the temperature of degenerate electron species significantly modify the basic features (i.e. speed, amplitude and width) of the solitary potential structures associated with degenerate pressure-driven nucleus-acoustic waves. The warm degenerate plasma model under consideration is applicable not only to all cold white dwarfs, but also to many hot white dwarfs, such as DQ white dwarfs, white dwarf H1504+65, white dwarf PG 0948+534, etc.

Subsonic and supersonic nucleus-acoustic solitary waves in thermally degenerate multi-nucleus plasma systems

A new thermally degenerate multi-nucleus plasma system (containing thermally degenerate electron species, non-degenerate warm light nucleus species, and low dense stationary heavy nucleus species) is considered. The basic features of arbitrary amplitude subsonic and supersonic solitary waves associated with thermally degenerate pressure-driven nucleus-acoustic waves in such a plasma system are studied by the pseudo-potential approach. The effects of the stationary heavy nucleus, non- and ultra-relativistically degenerate electron degeneracies, and light nucleus temperature on such arbitrary amplitude subsonic and supersonic solitary waves are also examined. It is found that (i) the presence of the heavy nucleus and Boltzmann distributed electron species supports the existence of subsonic solitary waves and the effects of electron degeneracies and light nucleus temperature reduce the possibility for the formation of these subsonic solitary waves; (ii) the amplitude (width) of these subsonic solitary waves increases (decreases) with the increase in the number density of the heavy nucleus species; (iii) the amplitude of the supersonic solitary waves in the situation of non-relativistically degenerate electron species is much smaller than that of the ultra-relativistically degenerate electron species but is much larger than that of the Boltzmann distributed electron species; (iv) their width in the situation of non-relativistically degenerate electron species is much wider than that of the ultra-relativistically degenerate electron species; and (v) their amplitude (width) decreases (increases) with the increase in the light nucleus temperature. The applications of the results in some degenerate astrophysical plasma systems and non-degenerate space plasma environments are discussed.

Nonlinear nucleus-acoustic waves in strongly coupled degenerate quantum plasmas

We report the evolutionary dynamics of nonlinear nucleus-acoustic wave patterns excitable in a strongly coupled self-gravitating complex quantum degenerate plasma (QDP) systems. It is inertially composed of strongly correlated non-degenerate heavy nuclei and weakly coupled degenerate light nuclei treated classically. It is thermally constituted of non-relativistic and ultra-relativistic degenerate lighter electrons behaving quantum mechanically. Application of nonlinear perturbation analysis results in a conjugated pair of extended Korteweg-de Vries (e-KdV) equations of unique mathematical shape. The constructed numerical tapestry shows the collective excitations of a new conjugational pair of nonlinear eigenmode structures of gravito-electrosatic origin. The electrostatic potential fluctuations evolve as a distinct family of stable periodic symmetric waves resembling regular soliton-antisoliton pulse-trains; in contrast, the gravitational counterparts evolve as a unique extended class of asymmetric oscillatory solitons and non-monotonous compressive dispersive asymmetric pulse-trains. The microphysical influential dependencies of the eigenstructural patterns on various sensible plasma multi-parametric factors are illustratively analyzed in both the non-relativistic (NR) and ultra-relativistic (UR) limits of the non-local quantum electronic dynamics. The applicability of the explored results in wave kinetic phenomenological processes naturalistically relevant in diversified compact astro-objects and their ambient hydrodynamic atmospheres is summarily outlined.

Nucleus-acoustic waves: Excitation, propagation, and stability

The propagatory excitation dynamics of the collective nucleus-acoustic waves supported in a strongly coupled self-gravitating degenerate quantum dusty plasma (QDP) system, widely realizable as the constitutive matter for white dwarfs and other compact astro-objects, is semi-analytically studied. The spherically symmetric QDP is composed of strongly coupled non-degenerate heavy nuclei, weakly coupled degenerate light nuclei, and non-relativistically and ultra-relativistically degenerate lighter electrons. A standard normal spherical mode analysis is applied to derive a complex generalized dispersion relation. A numerical illustrative calculation is executed in the ultra-low frequency approximation to see the dependency of various sensible parameters on the instability evolution. It is seen that the relative nuclear charge-mass coupling parameter (β) acts as a destabilizing and stabilizing agents in the non-relativistic (NR) and ultra-relativistic (UR) limits, respectively. The ratio of the charge density of heavy-to-light nuclear species (μ) acts as a destabilizer (stabilizer) in the NR (UR) limits, to the instability. The quantum parameter (H′) interestingly acts as a stabilizing agency in both the NR-UR limits.

Modulated heavy nucleus-acoustic waves and associated rogue waves in a degenerate relativistic quantum plasma system

A theoretical and numerical investigation has been carried out on amplitude modulated heavy nucleus-acoustic envelope solitons (HNAESs) in a degenerate relativistic quantum plasma (DRQP) system containing relativistically degenerate electrons and light nuclei, and non-degenerate mobile heavy nuclei. The cubic nonlinear Schrödinger equation, describing the nonlinear dynamics of the heavy nucleus-acoustic waves (HNAWs), is derived by employing a multi-scale perturbation technique. The dispersion relation for the HNAWs is derived, and the criteria for the occurrence of modulational instability of the HNAESs are analyzed. The localized structures (viz., envelope solitons and associated rogue waves) are found to be formed in the DRQP system under consideration. The basic features of the amplitude modulated HNAESs and associated rogue waves formed in realistic DRQP systems are briefly discussed.

Nucleus-acoustic envelope solitons and their modulational instability in a degenerate quantum plasma system

The existence and the basic features of nucleus-acoustic (NA) envelope bright and dark solitons in a degenerate quantum plasma system (DQPSs) (containing non-relativistically degenerate nuclei and inertialess ultra-relativistically degenerate electrons and positrons), have been theoretically investigated by deriving the nonlinear Schrödinger (NLS) equation. The reductive perturbation method, which is valid for a small but finite amplitude limit, is employed. The plasma parametric regimes for both modulationally stable and unstable NA waves (NAWs) are observed. It is found that the growth rate of the modulationally unstable NAWs is significantly modified by the number density of nucleus species. It is also observed that the modulationally stable (unstable) NAWs give rise to stable dark (bright) envelope solitons. The implications of our results obtained from our present investigation in astrophysical and laboratory DQPSs are briefly discussed.