Plasma Modes Along the Open Field Lines of a Neutron Star

We consider electrostatic plasma modes along the open field lines of a rotating neutron star. Goldreich-Julian charge density in general relativity is analyzed for the neutron star with zero inclination. It is found that the charge density is maximum at the polar cap and it remains almost same in certain extended region of the pole. For a steady state Goldreich-Julian charge density we found the usual plasma oscillation along the field lines; plasma frequency resembles to the gravitational redshift close to the Schwarzschild radius. We study the nonlinear plasma mode along the field lines. From the system of equations under general relativity, a second order differential equation is derived. The equation contains a term which describes the growing plasma modes near Schwarzschild radius in a black hole environment. The term vanishes with the distance far away from the gravitating object. For initially zero potential and field on the surface of a neutron star, Goldreich-Julian charge density is found to create the plasma mode, which is enhanced and propagates almost without damping along the open field lines. We briefly outline our plan to extend the work for studying soliton propagation along the open field lines of strongly gravitating objects

Langmuir dark solitons in dense ultrarelativistic electron-positron gravito-plasma in pulsar magnetosphere

Nonlinear propagation of electrostatic modes in ultrarelativistic dense elelectron-positron gravito-plasma at the polar cap region of pulsar magnetosphere is considered. A nonlinear Schr\"{o}dinger equation is obtained from the reductive perturbation method which predicts the existence of Langmuir dark solitons. Relevance of the propagating dark solitons to the pulsar radio emission is discussed.Comment: 6 pages, 7 figures. Accepted for publication in Astrophysics and Space Science. arXiv admin note: text overlap with arXiv:astro-ph/9808047 by other authors without attributio

Possible ion-acoustic soliton formation in the ionospheric perturbations observed on DEMETER before the 2007 Pu'er earthquake

The data of ionospheric perturbations observed on DEMETER before the 2007 Pu'er earthquake are analyzed. The three-component plasma (ions, electrons and heavy ions) is studied in the fluid concept. The linear dispersion relation for ion-acoustic wave is found in the presence of heavy ions. The nonlinear dynamics is studied for arbitrary amplitude of the wave. The Sagdeev potential is calculated, which shows that solitary structure exists for Mach number within a range defined by the presence of heavy ions. The developed ion-acoustic solitons may be used as precursor for earthquake prediction

Growing electrostatic modes in the isothermal pair plasma of the pulsar magnetosphere

It is shown that a strongly magnetized isothermal pair plasma near the surface of a pulsar supports low-frequency (in comparison to electron cyclotron frequency) toroidal electrostatic plasma modes in the equatorial region. Physically, the thermal pressure coupled with the magnetic pressure creates the low frequency oscillations which may grow for particular case of inhomogeneities of the equilibrium magnetic field and the pair plasma density.Comment: 8 pages, 8 figures, Accepted for publication in Astrophysics & Space Science 201

ON THE LANGMUIR OSCILLATION AND LANDAU DAMPING IN QUARK GLUON PLASMA

Abstract On the basis of semiclassical kinetic equations for quark-gluon plasma (QGP) and Yang-Mills equation in covariant gauge, Langmuir oscillation and linear Landau damping is investigated. It is found that plasma eigen modes are directly related with the wave number and it is highly coupled with the thermal part of QGP. The linear Landau damping also exists in QGP, which shows that plasma modes heavily damp for | k \-> 0

Reflection and trapping of Alfvén waves in the open field lines of a neutron star

We have studied Alfvén wave propagation in the polar cap region of a neutron star at isothermal atmosphere using linear MHD equations. The study demonstrates reflection and trapping of the wave from the steep gradient region of Alfvén speed. The trapping efficiency depends sensitively on a dimensionless parameter $\beta_{g}$ which is proportional to the mass and inversely proportional to thetemperature of the plasma. A scaling of radius, Schwarzchild radius and acceleration due to gravity of neutron stars of different masses are performed. The effective temperature of hydrostatic equilibrium is also scaled. For a neutron star with mass 1.4 solar mass and radius 10 km the temperature is to be of $10^8$ degree K. The Alfvén wave propagation near the event horizon is investigated. It is found that the wave length of Alfvén wave is shorter near the horizon while it becomes longer away from it. Pulsar wind acceleration by Alfvén wave is also examined. It is found that wave pressure force is predominant for low temperature but for higher temperature, thermal pressure is the main driving force

Arbitrary amplitude circularly polarized electromagnetic waves in electron positron magnetoplasmas

A class of exact nonlinear traveling wave solutions of the relativistic cold two-fluid model describing a one dimensional magnetized electron-positron plasma is presented. The solutions, which are circularly polarized transverse electromagnetic waves of arbitrary amplitude, propagate along the magnetic field and can be classified into nonlinear fast and slow waves