scholarly journals ALFVEN MODES DRIVEN NONLINEARLY BY METRIC PERTURBATIONS IN ANISOTROPIC MAGNETIZED COSMOLOGIES

2007 ◽  
Vol 22 (12) ◽  
pp. 2197-2209 ◽  
Author(s):  
APOSTOLOS KUIROUKIDIS ◽  
KOSTAS KLEIDIS ◽  
DEMETRIOS B. PAPADOPOULOS
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
High Frequency ◽  
Nonlinear Coupling ◽  
Quantum Vacuum ◽  
Pump Field ◽  
Vacuum Fluctuations ◽  
First Order ◽  
Density Perturbations ◽  
The Universe

We consider anisotropic magnetized cosmologies filled with conductive plasma fluid and study the implications of metric perturbations that propagate parallel to the ambient magnetic field. It is known that in the first-order (linear) approximation with respect to the amplitude of the perturbations no electric field and density perturbations arise. However when we consider the nonlinear coupling of the metric perturbations with their temporal derivatives, certain classes of solutions can induce steeply increasing in time, electric field perturbations. This is verified both numerically and analytically. The source of these perturbations can be either high-frequency quantum vacuum fluctuations, driven by the cosmological pump field, in the early stages of the evolution of the Universe, or astrophysical processes, or a nonlinear isotropization process, of an initially anisotropic cosmological space–time.

scholarly journals A New Inflationary Universe Scenario with Inhomogeneous Quantum Vacuum

2018 ◽  
Vol 2018 ◽  
pp. 1-15
Author(s):  
Yilin Chen ◽  
Jin Wang
Keyword(s):  
Green’S Function ◽  
Potential Barrier ◽  
Green's Function ◽  
Inflationary Universe ◽  
Quantum Vacuum ◽  
Vacuum Fluctuations ◽  
Inflationary Scenario ◽  
Slowing Down ◽  
The Universe ◽  
Inhomogeneous Quantum

We investigate the quantum vacuum and find that the fluctuations can lead to the inhomogeneous quantum vacuum. We find that the vacuum fluctuations can significantly influence the cosmological inhomogeneity, which is different from what was previously expected. By introducing the modified Green’s function, we reach a new inflationary scenario which can explain why the Universe is still expanding without slowing down. We also calculate the tunneling amplitude of the Universe based on the inhomogeneous vacuum. We find that the inhomogeneity can lead to the penetration of the Universe over the potential barrier faster than previously thought.

Gravitational waves and the (quantum) nature of the primordial seed

2014 ◽  
Vol 23 (12) ◽  
pp. 1441005 ◽  
Author(s):  
Rafael A. Porto
Keyword(s):  
Gravitational Waves ◽  
Large Scale ◽  
Direct Detection ◽  
Indirect Measurement ◽  
Effective Field ◽  
Quantum Vacuum ◽  
Vacuum Fluctuations ◽  
Early Universe Cosmology ◽  
New Generation ◽  
The Universe

At first glance, the (indirect) measurement of primordial tensor modes by the BICEP2 Collaboration supports an inflationary paradigm for early universe cosmology together with quantum vacuum fluctuations (aka gravitons) as the origin of the spectrum. In this paper, we argue the observed signal may instead be a signature of semiclassical sources of perturbations during inflation. In this scenario, despite a large tensor-to-scalar ratio r ≃ 0.2, it may be possible to write an effective field theory (EFT) of a rolling scalar field without super-Planckian excursions. If the results from BICEP2 withstand further scrutiny, measurements of primordial non-Gaussianity with large scale structure surveys, and direct detection of gravitational waves (GWs) with the new generation of observatories, will be of paramount importance to elucidate the (quantum) origin of structure in the universe.

scholarly journals Mapping of steady-state electric fields and convective drifts in geomagnetic fields – Part 2: The IGRF

2016 ◽  
Vol 34 (1) ◽  
pp. 67-73 ◽  
Author(s):  
A. D. M. Walker
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Field Line ◽  
Electric Fields ◽  
Rate Of Change ◽  
International Geomagnetic Reference Field ◽  
First Order ◽  
Faraday’S Law ◽  
Geomagnetic Fields ◽  
Field Lines

Abstract. A method of mapping electric fields along geomagnetic field lines is applied to the IGRF (International Geomagnetic Reference Field) model. The method involves integrating additional sets of first order differential equations simultaneously with those for tracing a magnetic field line. These provide a measure of the rate of change of the separation of two magnetic field lines separated by an infinitesimal amount. From the results of the integration Faraday's law is used to compute the electric field as a function of position along the field line. Examples of computations from a software package developed to implement the method are presented. This is expected to be of use in conjugate studies of magnetospheric phenomena such as SuperDARN (Super Dual Auroral Radar) observations of convection in conjugate hemispheres, or comparison of satellite electric field observations with fields measured in the ionosphere.

scholarly journals An Analogy Between the Effects of Fluctuating Electric Fields and Steady Magnetic Fields in Isotropic Conductors when a Universal Relaxation Time Cannot Be Defined

1960 ◽  
Vol 13 (1) ◽  
pp. 95
Author(s):  
EJ Moore
Keyword(s):  
Magnetic Field ◽  
Relaxation Time ◽  
Electric Field ◽  
Electric Fields ◽  
High Frequency ◽  
Present Note ◽  
Isotropic Solid ◽  
High Frequency Electric Field ◽  
Circular Frequency ◽  
Steady Magnetic Field

It is well known that when a " universal" time of relaxation ("t') exists, the influence of a harmonically varying electric field (F cceiOlt) on the transport properties of a solid may be taken into account by replacing "t' by "t'/(l +iCil"t'). Dingle (1956a) demonstrated that, for an isotropic solid, the effect of a steady magnetic field may similarly be obtained by replacing "t' by "t'/(l+j~l"t') with an applied d;c. electric field, and by "t'/[l+(iCil+jO)"t'] with an a.c. field. (Here j2= -1, ij -=1= -1, and 0=( -e)H/mc is the circular frequency of precession of an electron.) The object of the present note is to show that this analogy between a high frequency electric field and a steady magnetic field still exists, even when a " universal" relaxation time cannot be defined.

FROM VACUUM IN AN INFLATIONARY UNIVERSE TO FLUCTUATIONS IN THE MICROWAVE BACKGROUND: THE THREAD OF THE ARGUMENT

1994 ◽  
Vol 03 (01) ◽  
pp. 23-30
Author(s):  
NATHALIE DERUELLE ◽  
DAVID LANGLOIS ◽  
DAVID POLARSKI
Keyword(s):  
Background Radiation ◽  
Temperature Fluctuations ◽  
Inflationary Universe ◽  
Quantum Vacuum ◽  
Vacuum Fluctuations ◽  
Microwave Background ◽  
Evolution Of The Universe ◽  
Inflationary Phase ◽  
Microwave Background Radiation ◽  
The Universe

We sketch the logics of the argument which claims that the temperature fluctuations in the microwave background radiation, observed by the COBE satellite, have originated from quantum vacuum fluctuations in an early, inflationary phase of the evolution of the universe.

Electromagnetic modulations of electron whistlers in plasmas

1986 ◽  
Vol 36 (3) ◽  
pp. 447-452 ◽  
Author(s):  
L. Stenflo ◽  
M. Y. Yu ◽  
P. K. Shukla
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Nonlinear Equations ◽  
Plasma Heating ◽  
Whistler Wave ◽  
Nonlinear Coupling ◽  
Magnetic Fluctuations ◽  
Whistler Mode ◽  
Field Fluctuations ◽  
Magnetohydrodynamic Model

This paper presents a formulation of the nonlinear coupling of the electron whistler mode radiation with generalized (including higher frequencies than allowed by the magnetohydrodynamic model) magnetosonic fluctuations. A coupled set of nonlinear equations describing the interaction of the whistler wave electric field with the density and the field-aligned magnetic fluctuations of the generalized magnetosonic waves is derived and the problem of modula-tional instability is discussed. Our results have relevance to the non-thermal magnetic field fluctuations which lead to supplementary plasma heating.

A singular perturbation analysis of theoretical models for warm inhomogeneous plasmas

1971 ◽  
Vol 6 (2) ◽  
pp. 271-282 ◽  
Author(s):  
Robert M. Miura ◽  
Eugene M. Barston
Keyword(s):  
Electric Field ◽  
Singular Perturbation ◽  
High Frequency ◽  
Maxwell Equations ◽  
Perturbation Expansion ◽  
Theoretical Models ◽  
General Interest ◽  
First Order ◽  
Singular Perturbation Analysis ◽  
High Frequency Oscillations

Owing to the complexity of the Vlasov–Maxwell equations for inhomogeneous plasmas, it is of general interest to investigate simpler approximate models. We compare three specific models, proposed in the literature in connexion with the high frequency oscillations of such plasmas, by means of a singular perturbation expansion in powers of E = (λD/L)⅔, where λD and L are appropriate electron Debye and equilibrium scale lengths, respectively. Explicit formulas are obtained for the eigenfrequencies (to second order) and for the electric field eigenfunctions (to leading order), and the computation of these quantities for various equilibrium parameters becomes very simple indeed. We find that, whereas the electric field eigenfunctions differ in zero order for the three models, the eigenfrequencies are identical through first order.

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