Advances in Astrophysics

4

Authors: N. Chandra Wickramasinghe, Michael J. Rycroft

The transport of electrically charged bacterial-sized dust particles from the stratosphere to the high ionosphere is discussed. With the maximum electric field associated with the Global Electric Circuit during both active thunderstorm and fair weather conditions, we show that electric forces are inadequate to overcome gravity in lofting dust particles from the stratosphere to heights of ~ 400 km in the ionosphere, where they have recently been discovered at the orbit of the International Space Station.

13

Authors: Foisal B. T. Siddiki, A. A. Mamun, M. R. Amin

The basic features of linear and nonlinear quantum electron-acoustic (QEA) waves in a degenerate quantum plasma (containing non-relativistically degenerate electrons, superthermal or κ-distributed electrons, and stationary ions) are theoretically investigated. The nonlinear Schödinger (NLS) equation is derived by employing the reductive perturbation method. The stationary solitonic solution of the NLS equation is obtained, and examined analytically as well as numerically to identify the basic features of the QEA envelope solitons. It has been found that the effects of the degeneracy and exchange/Bohm potentials of cold electrons, and superthermality of hot electrons significantly modify the basic properties of linear and nonlinear QEA waves. It is observed that the QEA waves are modulationally unstable for k < kc, where kc is the maximum (critical) value of the QEA wave number k below which the QEA waves are modulationally unstable), and that for k < kc the solution of the NLS equation gives rise to the bright envelope solitons, which are found to be localized in both spatial (ξ) and time (τ ) axes. It is also observed that as the spectral index κ is increased, the critical value of the wave number (amplitude of the QEA envelope bright solitons) decreases (increases). The implications of our results should be useful in understanding the localized electrostatic perturbation in solid density plasma produced by irradiating metals by intense laser, semiconductor devices, microelectronics, etc.

14

Authors: A. Paul, G. Mandal, A. A. Mamun, M. R. Amin

The modulation instability of a dust ion-acoustic (DIA) wave in a highly collisional dusty plasma is studied theoretically. In this investigation, effects of ionization, ion loss, and electron superthermality on the DIA wave are included. By employing the standard reductive perturbation technique, a modified-nonlinear Schödinger equation (mNLSE) is developed for the evolution of the slowly varying amplitude of the DIA wave. A detailed analysis of the linear and nonlinear dispersions of the DIA wave is presented. Relevant to some astrophysical objects with typical parameters, it is found that the DIA wave is modulationally unstable below a certain critical wavenumber. Effects of the electron superthermality as well as the ionization and ion loss in the wave dynamics are also studied. It is found that the electron superthermality has a significant effect on the nonlinearity as well as on the damping of the DIA wave. It is also found that the critical wavenumber for the modulation instability is highly dependent on the parameter κ, known as the spectral index of the electron superthermality. Numerical results on the linear and nonlinear dispersions of the DIA wave are described. A parameter study on the Rouge wave solution of the mNLSE is also presented.

37

Authors: Boris V. Alexeev

The theory of the matter movement in black holes (BH) in the frame of non – local quantum hydrodynamics (NLQHD) is considered. The theory corresponds to the limit case when the matter density tends to infinity when the theory of General Relativity is not applicable in principle. From calculations follow that NLQHD equations for the black holes have the solutions limited in space. The domain of the solution existence is limited by the event horizon where gravity tends to infinity. It was shown: 1) internal perturbations in BH lead to the appearance of the packets of the gravitational waves. 2) The width of the wave packet is inversely proportional to the magnitude of internal energy. 3) Increasing of the internal energy leads to the transformation of the mode of antigravity into the attraction regime. 4) A strong mutual influence of the gravitational, antigravitational and electromagnetic fields exists. The velocity of gravitational waves is more than the speed of light. The numerical calculations of the Cauchy problem are delivered.