Colloquium: Nonlinear collective interactions in quantum plasmas with degenerate electron fluids

The current understanding of some important nonlinear collective processes in quantum plasmas with degenerate electrons is presented. After reviewing the basic properties of quantum plasmas, we present model equations (e.g. the quantum hydrodynamic and effective nonlinear Schr\"odinger-Poisson equations) that describe collective nonlinear phenomena at nanoscales. The effects of the electron degeneracy arise due to Heisenberg's uncertainty principle and Pauli's exclusion principle for overlapping electron wavefunctions that result in tunneling of electrons and the electron degeneracy pressure. Since electrons are Fermions (spin-1/2), there also appears an electron spin current and a spin force acting on electrons due to the Bohr magnetization. The quantum effects produce new aspects of electrostatic (ES) and electromagnetic (EM) waves in a quantum plasma that are summarized in here. Furthermore, we discuss nonlinear features of ES ion waves and electron plasma oscillations (ESOs), as well as the trapping of intense EM waves in quantum electron density cavities. Specifically, simulation studies of the coupled nonlinear Schr\"odinger (NLS) and Poisson equations reveal the formation and dynamics of localized ES structures at nanoscales in a quantum plasma. We also discuss the effect of an external magnetic field on the plasma wave spectra and develop quantum magnetohydrodynamic (Q-MHD) equations. The results are useful for understanding numerous collective phenomena in quantum plasmas, such as those in compact astrophysical objects, in plasma-assisted nanotechnology, and in the next-generation of intense laser-solid density plasma interaction experiments.Comment: 25 pages, 14 figures. To be published in Reviews of Modern Physic

Cold quantum gases: coherent quantum phenomena from Bose-Einstein condensation to BCS pairing of fermions

Studies of trapped quantum gases of bosons and of fermions have opened up a new range of many-body problems, having a strong overlap with nuclear and neutron star physics. Topics discussed here include: the Bose yrast problem -- how many-particle Bose systems carry extreme amounts of angular momentum; the infrared divergent structure of the transition to Bose condensation in a weakly interacting system; and the physics of extremely strongly interacting Bose and Fermi systems, in the scale-free regime where the two body s-wave scattering lengths are large compared with the interparticle spacing. Such a regime is realized experimentally through use of atomic Feshbach resonances. Finally we discuss creation of BCS-paired states in trapped Fermi gases.Comment: Proceedings INPC-2004, 18 pages, 7 figure

Scalings of the synchrotron cut-off and turbulent correlation of active galactic nucleus jets

We propose a new analytic scaling of the cut-off frequency of synchrotron radiation from active galactic nucleus (AGN) jets that are nonuniformly filled with many filaments. The theoretical upper limit is provided independent of magnetic intensity, spectral index, coherence and correlation length of filamentary turbulence, etc., such that \nu_c\simeq 6\times 10^{20}\delta[(r-1)/r]^{4/3}(b/10^{-4}) Hz, where \delta, r and b are the Doppler beaming factor, shock-compression ratio and energy-density ratio of the perturbed/local mean magnetic field of the filaments, respectively. Combining our results with observational data for 18 extragalactic sources, a constraint on the filament correlation length is found, in order to give the number scaling of filaments. The results suggest that, in particular, the jets of compact BL Lacs possess a large number of filaments with transverse size scale smaller than the emission-region size. The novel concept of the quantization of flowing plasma is suggested.Comment: 8 pages, 4 figures, accepted for publication in MNRA

Atmospheres and radiating surfaces of neutron stars with strong magnetic fields

We review the current status of the theory of thermal emission from the surface layers of neutron stars with strong magnetic fields $B\sim 10^{10}-10^{15}$ G, including formation of the spectrum in a partially ionized atmosphere and at a condensed surface. In particular, we describe recent progress in modeling partially ionized atmospheres of central compact objects in supernova remnants, which may have moderately strong fields $B\sim 10^{10}-10^{11}$ G. Special attention is given to polarization of thermal radiation emitted by a neutron star surface. Finally, we briefly describe applications of the theory to observations of thermally emitting isolated neutron stars.Comment: 27 pages, 5 figures, invited review at the conference "The Modern Physics of Compact Stars 2015" (Yerevan, Armenia, Sept. 30 - Oct. 3, 2015), edited by R. Avagyan, A. Saharian, and A. Sedrakian. In v.2, a citation (Ref.114) is correcte

The Non-Euclidean Hydrodynamic Klein-Gordon Equation with Perturbative Self-Interacting Field

In this paper the quantum hydrodynamic approach for the KGE owning a perturbative self-interaction term is developed. The generalized model to non-Euclidean space-time allows to determine the quantum energy impulse tensor density of mesons for the gravitational equation of quantum mechanical systems.Comment: 11 page