scholarly journals Particle Production via Dirac Dipole Moments in the Magnetized and Nonmagnetized Exponentially Expanding Universe

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Semra Gurtas Dogan ◽  
Ganim Gecim ◽  
Yusuf Sucu
Keyword(s):  
Magnetic Field ◽  
Decomposition Method ◽  
Particle Production ◽  
Dipole Moments ◽  
Dirac Particle ◽  
Future Time ◽  
Magnetization Density ◽  
Total Polarization ◽  
The Universe ◽  
The Magnetic Field

In the present paper, we solve the Dirac equation in the 2+1 dimensional exponentially expanding magnetized by uniform magnetic field and nonmagnetized universes, separately. Asymptotic behaviors of the solutions are determined. Using these results we discuss the current of a Dirac particle to discuss the polarization densities and the magnetization density in the context of Gordon decomposition method. In this work we also calculate the total polarization and magnetization, to investigate how the magnetic field affects the particle production. Furthermore, the electric and the magnetic dipole moments are calculated, and based on these, we have discussed the effects of the dipole moments on the charge distribution of the universe and its conductivity for both the early and the future time epoch in the presence/absence of a constant magnetic field and exponentially expanding spacetime.

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 Magnetic and Dielectric Properties of Nano- and Micron-BiFeO3/LDPE Composites with Magnetization Treatments

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 120
Author(s):  
Wei Song ◽  
Yu-Zhang Fan ◽  
Yu Hua ◽  
Wei-Feng Sun
Keyword(s):  
Magnetic Field ◽  
Dielectric Properties ◽  
Ambient Temperature ◽  
Elevated Temperatures ◽  
Dipole Moments ◽  
Magnetic Interactions ◽  
Magnetic Field Direction ◽  
Magnetic And Dielectric Properties ◽  
Ldpe Composites ◽  
The Magnetic Field

By means of magnetization treatments at ambient temperature and elevated temperatures, the nano- and micron-bismuth ferrate/low density polyethylene (BiFeO3/LDPE) dielectric composites are developed to explore the material processing method to modify the crystalline morphology, magnetic and dielectric properties. The magnetic field treatment can induce the dipole in the LDPE macromolecular chain which leads to preferred orientation of polyethylene crystal grains to the direction of the magnetization field. The surface morphology of the materials measured by atomic force microscope (AFM) implies that the LDPE macromolecular chains in BiFeO3/LDPE composites have been orderly arranged and form thicker lamellae accumulated with a larger spacing after high temperature magnetization, resulting in the increased dimension and orientation of spherulites. The residual magnetization intensities of BiFeO3/LDPE composites have been significantly improved by magnetization treatments at ambient temperature. After this magnetization at ambient temperature, the MR of nano- and micron-BiFeO3/LDPE composites approach to 4.415 × 10−3 and 0.690 × 10−3 emu/g, respectively. The magnetic moments of BiFeO3 fillers are arranged parallel to the magnetic field direction, leading to appreciable enhancement of the magnetic interactions between BiFeO3 fillers, which will inhibit the polarization of the electric dipole moments at the interface between BiFeO3 fillers and the LDPE matrix. Therefore, magnetization treatment results in the lower dielectric constant and higher dielectric loss of BiFeO3/LDPE composites. It is proven that the magnetic and dielectric properties of polymer dielectric composites can be effectively modified by the magnetization treatment in the melt blending process of preparing composites, which is expected to provide a technical strategy for developing magnetic polymer dielectrics.

scholarly journals General relativistic magnetic perturbations and dynamo effects in extragalactic radiosources

2010 ◽  
Vol 6 (S274) ◽  
pp. 393-397
Author(s):  
L. C. Garcia de Andrade
Keyword(s):  
Magnetic Field ◽  
Magnetic Energy ◽  
Magnetic Fluctuations ◽  
Dynamo Action ◽  
Magnetic Contrast ◽  
Mhd Dynamo ◽  
Curvature Energy ◽  
Induction Equation ◽  
The Universe ◽  
The Magnetic Field

AbstractBy making use of the MHD self-induction equation in general relativity (GR), recently derived by Clarkson and Marklund (2005), it is shown that when Friedmann universe possesses a spatial section whose Riemannian curvature is negative, the magnetic energy bounds computed by Nuñez (2002) also bounds the growth rate of the magnetic field given by the strain matrix of dynamo flow. Since in GR-MHD dynamo equation, the Ricci tensor couples with the universe magnetic field, only through diffusion, and most ages are highly conductive the interest is more theoretical here, and only very specific plasma astrophysical problems can be address such as in laboratory plasmas. Magnetic fields and the negative curvature of some isotropic cosmologies, contribute to enhence the amplification of the magnetic field. Ricci curvature energy is shown to add to strain matrix of the flow, to enhance dynamo action in the universe. Magnetic fluctuations of the Clarkson-Marklund equations for a constant magnetic field seed in highly conductive flat universes, leads to a magnetic contrast of ≈ 2, which is well within observational limits from extragalactic radiosources of ≈ 1.7. In the magnetic helicity fluctuations the magnetic contrast shows that the dynamo effects can be driven by these fluctuations.

scholarly journals Magnetic Field Evolution in Neutron Star Crusts: Beyond the Hall Effect

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 130
Author(s):  
Konstantinos N. Gourgouliatos ◽  
Davide De Grandis ◽  
Andrei Igoshev
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Hall Effect ◽  
Thermal Emission ◽  
Ohmic Dissipation ◽  
Field Evolution ◽  
The Universe ◽  
The Magnetic Field ◽  
Maxwell Stresses

Neutron stars host the strongest magnetic fields that we know of in the Universe. Their magnetic fields are the main means of generating their radiation, either magnetospheric or through the crust. Moreover, the evolution of the magnetic field has been intimately related to explosive events of magnetars, which host strong magnetic fields, and their persistent thermal emission. The evolution of the magnetic field in the crusts of neutron stars has been described within the framework of the Hall effect and Ohmic dissipation. Yet, this description is limited by the fact that the Maxwell stresses exerted on the crusts of strongly magnetised neutron stars may lead to failure and temperature variations. In the former case, a failed crust does not completely fulfil the necessary conditions for the Hall effect. In the latter, the variations of temperature are strongly related to the magnetic field evolution. Finally, sharp gradients of the star’s temperature may activate battery terms and alter the magnetic field structure, especially in weakly magnetised neutron stars. In this review, we discuss the recent progress made on these effects. We argue that these phenomena are likely to provide novel insight into our understanding of neutron stars and their observable properties.

scholarly journals Implications of baryon–dark matter interaction on IGM temperature and tSZ effect with magnetic field

2020 ◽  
Vol 500 (1) ◽  
pp. 643-654
Author(s):  
Arun Kumar Pandey ◽  
Sunil Malik ◽  
T R Seshadri
Keyword(s):  
Magnetic Field ◽  
Dark Matter ◽  
Interaction Cross Section ◽  
Ionization State ◽  
Microwave Background ◽  
Magnetic Turbulence ◽  
Matter Interaction ◽  
Ionization Fraction ◽  
The Universe ◽  
The Magnetic Field

ABSTRACT We show that the combined effect of cosmic magnetic field and a possible non-standard interaction between baryons and dark matter (DM) has interesting consequences on the thermal Sunyaev−Zel’dovich (tSZ) effect depending on the temperature and the ionization state of the intergalactic medium. The drag force between the baryons and DM due to the relative velocity between them, and their temperature difference results in heat transfer between these two species. At the same time, the ambipolar diffusion and the decaying magnetic turbulence tends to heat up the baryons. This interplay of these two processes give rise to different evolution histories of the thermal and ionization state of the universe and hence influences the cosmic microwave background (CMB) spectrum at small scales through the tSZ effect. In this work, we have computed the evolution of the temperature, ionization fraction, and the y-parameter of the CMB for different strengths of the magnetic field and the interaction cross-section. We note that the y-parameter can be significantly enhanced with the inclusion of magnetic field and baryon–DM interaction as compared to the case when these are absent. The enhancement depends on the strength of the magnetic field.

Simulation of Plasma Flow Injection with Multi-Hierarchy Model Aiming Magnetic Reconnection Studies

2012 ◽  
Vol 11 (3) ◽  
pp. 1006-10210 ◽  
Author(s):  
S. Usami ◽  
H. Ohtani ◽  
R. Horiuchi ◽  
M. Den
Keyword(s):  
Magnetic Field ◽  
Simulation Model ◽  
Magnetic Reconnection ◽  
Flow Injection ◽  
Plasma Flow ◽  
Decomposition Method ◽  
Domain Decomposition Method ◽  
Particle In Cell ◽  
Hierarchy Model ◽  
The Magnetic Field

AbstractA multi-hierarchy simulation model aiming magnetic reconnection studies is developed and improved in which macroscopic and microscopic physics are computed consistently and simultaneously. Macroscopic physics is solved by mag-netohydrodynamics (MHD) algorithm, while microscopic dynamics is expressed by particle-in-cell (PIC) algorithm. The multi-hierarchy model relies on the domain decomposition method, and macro- and micro-hierarchies are interlocked smoothly by hand-shake scheme. As examination, plasma flow injection is simulated in the multi-hierarchy model. It is observed that plasmas flow from a macro-hierarchy to a micro-hierarchy across the magnetic field smoothly and continuously.

THE CHANGES OF PHYSICAL PROPERTIES OF WATER ARISING FROM THE MAGNETIC FIELD AND ITS MECHANISM

2013 ◽  
Vol 27 (31) ◽  
pp. 1350228 ◽  
Author(s):  
XIAO-FENG PANG ◽  
GUI-FA SHEN
Keyword(s):  
Magnetic Field ◽  
Dielectric Constant ◽  
Electromagnetic Field ◽  
Electric Conductivity ◽  
Dipole Moments ◽  
Electromagnetic Properties ◽  
Magnetized Water ◽  
Charged Ions ◽  
The Magnetic Field ◽  
Important Significance

In this paper, the influences of magnetic field on electromagnetic properties of water are experimentally investigated. The results clearly show that the magnetic field reduces the dielectric constant and resistance of water and increases its electric conductivity. In this study, we also find that the electric conductivity of magnetized water increases with increasing the frequency of externally applied electromagnetic field and magnetized time, but its dielectric constant and resistance are decreased with increasing the frequency of electromagnetic field and magnetized time of water. Then we can affirm that the magnetic field changes the electric properties of water. Finally, we discuss the mechanism of variation of electromagnetic properties in water, which are due to the changes of nature of charged ions and velocity of hydrogen ions as well as the changes of polarized features or dipole moments of free molecules and clusters including linear and ring hydrogen-bond chains of molecules in water under the influences of electromagnetic fields. Therefore, this study has important significance in science and can expand the applications of magnetized water in biomedicine and industry.

scholarly journals MAGNETIC FIELDS IN ACCRETION DISCS AROUND NEUTRON STARS — CONSEQUENCES FOR THE CHANGE OF SPIN

2013 ◽  
Vol 23 ◽  
pp. 106-110
Author(s):  
LUCA NASO ◽  
JOHN MILLER ◽  
WLODEK KLUŹNIAK
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Accretion Disk ◽  
Accretion Disks ◽  
Magnetic Field Profile ◽  
History Of ◽  
The One ◽  
The Universe ◽  
The Magnetic Field

Accretion disks are ubiquitous in the universe and it is generally accepted that magnetic fields play a pivotal role in accretion-disk physics. The spin history of millisecond pulsars, which are usually classified as magnetized neutron stars spun up by an accretion disk, depends sensitively on the magnetic field structure, and yet highly idealized models from the 80s are still being used for calculating the magnetic field components. We present a possible way of improving the currently used models with a semi-analytic approach. The resulting magnetic field profile of both the poloidal and the toroidal component can be very different from the one suggested previously. This might dramatically change our picture of which parts of the disk tend to spin the star up or down.

scholarly journals Numerical Study of the Magnetic Field Effect on Ferromagnetic Fluid Flow and Heat Transfer in a Square Porous Cavity

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3235 ◽  
Author(s):  
Mohamed El-Amin ◽  
Usama Khaled ◽  
Abderrahmane Beroual
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Fluid Flow ◽  
Numerical Study ◽  
Mass Transfer Rate ◽  
Porous Cavity ◽  
Flow And Heat Transfer ◽  
Magnetization Density ◽  
Ferromagnetic Fluid ◽  
The Magnetic Field

A numerical study of ferromagnetic-fluid flow and heat transfer in a square porous cavity under the effect of a magnetic field is presented. The water-magnetic particle suspension is treated as a miscible mixture and, thus, the magnetization, density and viscosity of the ferrofluid are obtained. The governing partial-differential equations were solved numerically using the cell-centered finite-difference method for the spatial discretization, while the multiscale time-splitting implicit method was developed to treat the temporal discretization. The Courant–Friedrichs–Lewy stability condition (CFL < 1) was used to make the scheme adaptive by dividing time steps as needed. Two cases corresponding to Dirichlet and Neumann boundary conditions were considered. The efficiency of the developed algorithm as well as some physical results such as temperature, concentration, and pressure; and the local Nusselt and Sherwood numbers at the cavity walls are presented and discussed. It was noticed that the particle concentration and local heat/mass transfer rate are related to the magnetic field strength, and both pressure and velocity increase as the strength of the magnetic was increased.

The magnetization of [Fe(OD 2 ) 6 ] 2+ in ammonium ferrous Tutton salt studied by polarized neutron diffraction - a canted paramagnet

1990 ◽  
Vol 428 (1874) ◽  
pp. 113-127 ◽  
Keyword(s):  
Magnetic Field ◽  
Neutron Diffraction ◽  
Iron Atom ◽  
Magnetic Data ◽  
Ligand Field ◽  
Magnetization Direction ◽  
Magnetization Density ◽  
Magnetic Structure Factor ◽  
Polarized Neutron ◽  
The Magnetic Field

A polarized neutron diffraction experiment has been done on deuterated ammonium ferrous Tutton salt at 1.5 K, 4.6 T with orientations of the magnetic field along the crystal b and c * axes. The flipping ratios of 303 and 280 reflections respectively were used, after correction for extinction, to give 121 and 118 unique values of the magnetic structure factor F M, Z (hkl) (eff). Those values were used in refinements of models for a description of the magnetization density in the crystal. All models resulted in substantial (37° and 45°) canting of the magnetization direction in the paramagnet away from the magnetic field, to an almost constant direction with respect to the O 6 ligand framework, indicating large magnetic anisotropy at the iron atom sites. There is delocalization of magnetization density away from the iron atom into the Fe-O overlap region ( — 4.5%) and onto the OD 2 ligands (6.5%), values comparable with the delocalization of spin from the metal atom in other Tutton salts studied. An earlier ligand field model for the electronic structure of the ion based upon spectroscopic and magnetic data is shown to be inadequate, because it is incompatible with the observed anisotropy in the magnetization around the iron atoms.

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