Hertz potential formalism for force-free electrodynamics and its application to Brennan–Gralla–Jacobson solutions

2016 ◽  
Vol 25 (03) ◽  
pp. 1650039
Author(s):  
Xiaokai He ◽  
Zhoujian Cao
Keyword(s):  
Magnetic Field ◽  
Maxwell Equations ◽  
Dynamical Equations ◽  
Free Model ◽  
Hertz Potential ◽  
Free Case ◽  
Potential Formalism ◽  
Inertial Energy ◽  
The Universe ◽  
Schwarzschild Background

The Hertz potential is a powerful tool for the source-free electrodynamics. Especially for the algebraically special spacetime background, the Hertz potential formalism simplifies the Maxwell equations quite much. In astrophysics, strong electric–magnetic field is very common. Force-free electrodynamics is a good approximation for strong enough electric–magnetic field compared to the inertial energy of the involved plasma. For example, the force-free model has been extensively used to describe the magnetosphere of stars in the universe. In this paper, we extend the Hertz potential formalism to the force-free electrodynamics. The Hertz potential formalism simplifies the force-free dynamical equations as much as that in the source-free case. As an application, we use the Hertz potential formalism to the Schwarzschild background. And the Brennan–Gralla–Jacobson solutions are recovered straightforwardly.

scholarly journals ELECTROMAGNETIC FIELDS OF CHARGED AND MAGNETIZED CYLINDRICAL CONDUCTORS IN NUT SPACE

2005 ◽  
Vol 14 (03n04) ◽  
pp. 687-695 ◽  
Author(s):  
B. J. AHMEDOV ◽  
A. V. KHUGAEV ◽  
N. I. RAKHMATOV
Keyword(s):  
Magnetic Field ◽  
Gravitational Field ◽  
Electromagnetic Fields ◽  
Electric Charge ◽  
Maxwell Equations ◽  
Analytic Solutions ◽  
Vertical Magnetic Field ◽  
General Relativistic ◽  
Azimuthal Current ◽  
Cylindrical Conductors

We present analytic solutions of Maxwell equations for infinitely long cylindrical conductors with nonvanishing electric charge and currents in the external background spacetime of a line gravitomagnetic monopole. It has been shown that vertical magnetic field arising around cylindrical conducting shell carrying azimuthal current will be modified by the gravitational field of NUT source. We obtain that the purely general relativistic magnetic field which has no Newtonian analog will be produced around charged gravitomagnetic monopole.

Impact of partially thermal electrons on the propagation characteristics of extraordinary mode in relativistic regime

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Syeda Noureen
Keyword(s):  
Magnetic Field ◽  
Maxwell Equations ◽  
Relativistic Quantum ◽  
The Novel ◽  
Propagation Characteristics ◽  
Relativistic Limit ◽  
Long Wavelength ◽  
Relativistic Regime ◽  
Dirac Distribution ◽  
Relativistic Fermi

Abstract On employing linearized Vlasov–Maxwell equations the solution of relativistic electromagnetic extraordinary mode is investigated for the wave propagating perpendicular to a uniform ambient magnetic field (in the presence of arbitrary magnetic field limit i.e., ω > Ω > k.v) in partially degenerate (i.e., for T F ≥ T and T ≠ 0) electron plasma under long wavelength limit (ω ≫ k.v). Due to the inclusion of weak quantum degeneracy the relativistic Fermi–Dirac distribution function is expanded under the relativistic limit ( m 0 2 c 2 2 p 2 < 1 $\frac{{m}_{0}^{2}{c}^{2}}{2{p}^{2}}{< }1$ ) to perform momentum integrations which generate the Polylog functions. The propagation characteristics and shifting of cutoff points of the extraordinary mode are examined in different relativistic density and magnetic field ranges. The novel graphical results of extraordinary mode in relativistic quantum partially degenerate (for μ T = 0 $\frac{\mu }{T}=0$ ), nondegenerate (for μ T ≈ − 1 $\frac{\mu }{T}\approx -1$ ) and fully/completely degenerate (for μ T ≈ $\frac{\mu }{T}\approx $ 1) environments are obtained and the previously reported results are retraced as well.

scholarly journals Can accelerated expansion of the universe be due to spacetime vorticity?

2018 ◽  
Vol 33 (40) ◽  
pp. 1850240
Author(s):  
Babur M. Mirza
Keyword(s):  
Magnetic Field ◽  
Accelerated Expansion ◽  
Newtonian Gravity ◽  
Hubble’S Parameter ◽  
Cosmic Expansion ◽  
Zero Curvature ◽  
Expansion Of The Universe ◽  
General Relativistic ◽  
The Universe ◽  
The Magnetic Field

We present here a general relativistic mechanism for accelerated cosmic expansion and the Hubble’s parameter. It is shown that spacetime vorticity coupled to the magnetic field density in galaxies causes the galaxies to recede from one another at a rate equal to the Hubble’s constant. We therefore predict an oscillatory universe, with zero curvature, without assuming violation of Newtonian gravity at large distances or invoking dark energy/dark matter hypotheses. The value of the Hubble’s constant, along with the scale of expansion, as well as the high isotropy of CMB radiation are deduced from the model.

scholarly journals De Sitter and power-law solutions in non-local Gauss–Bonnet gravity

2018 ◽  
Vol 15 (11) ◽  
pp. 1850188 ◽  
Author(s):  
E. Elizalde ◽  
S. D. Odintsov ◽  
E. O. Pozdeeva ◽  
S. Yu. Vernov
Keyword(s):  
Power Law ◽  
Sufficient Conditions ◽  
Model Parameters ◽  
Local Form ◽  
De Sitter ◽  
Dynamical Equations ◽  
Non Local ◽  
Necessary And Sufficient ◽  
The Universe ◽  
Universe Evolution

The cosmological dynamics of a non-locally corrected gravity theory, involving a power of the inverse d’Alembertian, is investigated. Casting the dynamical equations into local form, the fixed points of the models are derived, as well as corresponding de Sitter and power-law solutions. Necessary and sufficient conditions on the model parameters for the existence of de Sitter solutions are obtained. The possible existence of power-law solutions is investigated, and it is proven that models with de Sitter solutions have no power-law solutions. A model is found, which allows to describe the matter-dominated phase of the Universe evolution.

A MODEL HIERARCHY FOR IONOSPHERIC PLASMA MODELING

2004 ◽  
Vol 14 (03) ◽  
pp. 393-415 ◽  
Author(s):  
CHRISTOPHE BESSE ◽  
PIERRE DEGOND ◽  
FABRICE DELUZET ◽  
JEAN CLAUDEL ◽  
GÉRARD GALLICE ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Plasma Density ◽  
Maxwell Equations ◽  
Ionospheric Plasma ◽  
Practical Interest ◽  
Plasma Modeling ◽  
Model Hierarchy ◽  
Great Practical Interest ◽  
Two Fluid ◽  
Insight Into

This paper deals with the modeling of the ionospheric plasma. Starting from the two-fluid Euler–Maxwell equations, we present two hierarchies of models. The MHD hierarchy deals with large plasma density situations while the dynamo hierarchy is adapted to lower density situations. Most of the models encompassed by the dynamo hierarchy are classical ones, but we shall give a unified presentation of them which brings a new insight into their interrelations. By contrast, the MHD hierarchy involves a new (at least to the authors) model, the massless-MHD model. This is a diffusion system for the density and magnetic field which could be of great practical interest. Both hierarchies terminate with the "classical" Striation model, which we shall investigate in detail.

Helical Magnetic Cavities: Kinetic Model and Comparison with MMS Observations

2021 ◽  
Author(s):  
Jinghuan Li ◽  
Xuzhi Zhou ◽  
Fan Yang ◽  
Anton V. Artemyev ◽  
Qiugang Zong
Keyword(s):  
Magnetic Field ◽  
Kinetic Model ◽  
Pitch Angle ◽  
Maxwell Equations ◽  
Equilibrium Solution ◽  
Space Plasma ◽  
Azimuthal Magnetic Field ◽  
Particle Distributions ◽  
Multi Scale ◽  
Self Consistent

&lt;p&gt;Magnetic cavities are sudden depressions of magnetic field strength widely observed in the space plasma environments, which are often accompanied by plasma density and pressure enhancement. To describe these cavities, a self-consistent kinetic model has been proposed as an equilibrium solution to the Vlasov-Maxwell equations. However, observations from the Magnetospheric Multi-Scale (MMS) constellation have shown the existence of helical magnetic cavities characterized by the presence of azimuthal magnetic field, which could not be reconstructed by the aforementioned model. Here, we take into account another invariant of motion, the canonical axial momentum, to construct the particle distributions and accordingly modify the equilibrium model. The reconstructed magnetic cavity shows excellent agreement with the MMS1 observations not only in the electromagnetic field and plasma moment profiles but also in electron pitch-angle distributions. With the same set of parameters, the model also predicts signatures of the neighboring MMS3 spacecraft, matching its observations satisfactorily.&lt;/p&gt;

scholarly journals On the flux of high-energy cosmogenic neutrinos and the influence of the extragalactic magnetic field

2019 ◽  
Vol 488 (1) ◽  
pp. L119-L122 ◽  
Author(s):  
David Wittkowski ◽  
Karl-Heinz Kampert
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Large Scale ◽  
Neutrino Flux ◽  
Cosmic Ray ◽  
High Energy ◽  
Observation Time ◽  
Cosmological Time ◽  
Cosmic Background ◽  
The Universe

ABSTRACT Cosmogenic neutrinos originate from interactions of cosmic rays propagating through the universe with cosmic background photons. Since both high-energy cosmic rays and cosmic background photons exist, the existence of high-energy cosmogenic neutrinos is certain. However, their flux has not been measured so far. Therefore, we calculated the flux of high-energy cosmogenic neutrinos arriving at the Earth on the basis of elaborate 4D simulations that take into account three spatial degrees of freedom and the cosmological time-evolution of the universe. Our predictions for this neutrino flux are consistent with the recent upper limits obtained from large-scale cosmic-ray experiments. We also show that the extragalactic magnetic field has a strong influence on the neutrino flux. The results of this work are important for the design of future neutrino observatories, since they allow to assess the detector volume and observation time that are necessary to detect high-energy cosmogenic neutrinos in the near future. An observation of such neutrinos would push multimessenger astronomy to hitherto unachieved energy scales.

scholarly journals CYCLIC MAGNETIC UNIVERSE

2009 ◽  
Vol 24 (30) ◽  
pp. 5639-5658 ◽  
Author(s):  
M. NOVELLO ◽  
ALINE N. ARAUJO ◽  
J. M. SALIM
Keyword(s):  
Magnetic Field ◽  
Present Model ◽  
Nonlinear Electrodynamics ◽  
Acceleration Phase ◽  
Maxwell Theory ◽  
Cosmological Scenario ◽  
One Step ◽  
The Universe ◽  
Friedmann Robertson Walker ◽  
Main Factor

Recent works have shown the important role nonlinear electrodynamics (NLED) can have in two crucial questions of cosmology, concerning particular moments of its evolution for very large and for low-curvature regimes, that is for very condensed phase and at the present period of acceleration. We present here a toy model of a complete cosmological scenario in which the main factor responsible for the geometry is a nonlinear magnetic field which produces a Friedmann–Robertson–Walker homogeneous and isotropic geometry. In this scenario we distinguish four distinct phases: a bouncing period, a radiation era, an acceleration era, and a re-bouncing period. It has already been shown that in NLED a strong magnetic field can overcome the inevitability of a singular region typical of linear Maxwell theory; on the other extreme situation, that is for very weak magnetic field it can accelerate the expansion. The present model goes one step further: after the acceleration phase the universe re-bounces and enters into a collapse era. This behavior is a manifestation of the invariance under the dual map of the scale factor a(t) → 1/a(t), a consequence of the corresponding inverse symmetry of the electromagnetic field (F → 1/F, where F ≡ FμνFμν) of the NLED theory presented here. Such sequence collapse–bouncing–expansion–acceleration–re-bouncing–collapse constitutes a basic unitary element for the structure of the universe that can be repeated indefinitely yielding what we call a cyclic magnetic universe.

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