QUASI-STATIONARY ELECTROMAGNETIC EFFECTS IN CONDUCTORS AND SUPERCONDUCTORS IN SCHWARZSCHILD SPACE–TIME

2005 ◽  
Vol 14 (05) ◽  
pp. 817-835 ◽  
Author(s):  
B. J. AHMEDOV ◽  
F. J. FATTOYEV
Keyword(s):  
Magnetic Field ◽  
Gravitational Field ◽  
Neutron Stars ◽  
Penetration Depth ◽  
Skin Effect ◽  
Outer Core ◽  
Point Of View ◽  
Time Dependent ◽  
General Relativistic ◽  
Stationary Gravitational Field

The general principles needed to compute the effect of a stationary gravitational field on the quasistationary electromagnetic phenomena in normal conductors and superconductors are formulated from general relativistic point of view. Generalization of the skin effect, that is the general relativistic modification of the penetration depth (of the time-dependent magnetic field in the conductor) due to its relativistic coupling to the gravitational field is obtained. The effect of the gravitational field on the penetration and coherence depths in superconductors is also studied. As an illustration of the foregoing general results, we discuss their application to superconducting systems in the outer core of neutron stars. The relevance of these effects to electrodynamics of magnetized neutron stars has been shown.

scholarly journals The Gravitomagnetic Effects in Rapidly Rotating Neutron Stars: A Theoretical Study

2020 ◽  
Vol 2 (2) ◽  
pp. 149-157
Author(s):  
Atsnaita Yasrina ◽  
Nugroho Adi Pramono
Keyword(s):  
Magnetic Field ◽  
Gravitational Field ◽  
Neutron Star ◽  
Neutron Stars ◽  
Strong Magnetic Field ◽  
Rotational Speed ◽  
Distribution Density ◽  
Theoretical Study ◽  
Electromagnetic Measurements ◽  
General Relativistic

Electromagnetic measurements of a general relativistic gravitomagnetic effect can be done within the conductor embedded in a rotating gravitational object’s spacetime. Neutron stars are rotating gravitational object that have strong magnetic field. The gravitomagnetic effect in a neutron star can be determined from the distribution density in the conductor. Neutron star is assumed as a conductor and it rotates rapidly. The distribution density inside the conductor is obtained from the electromagnetic contravariant tensor and the relativistic rotational speed of the conductor. It has obtained the distribution density inside the conductor for the rapidly rotating neutron star. The results are compared to the slowly rotating neutron star which depends on the angular veolocity and the gravitational field.

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.

scholarly journals 1S0 Pairing Gaps, Chemical Potentials and Entrainment Matrix in Superfluid Neutron-Star Cores for the Brussels–Montreal Functionals

Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 470
Author(s):  
Valentin Allard ◽  
Nicolas Chamel
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Physical Meaning ◽  
Outer Core ◽  
Time Dependent ◽  
Hartree Fock ◽  
Chemical Potentials ◽  
Bogoliubov Equations ◽  
Flow Velocities

Temperature and velocity-dependent 1S0 pairing gaps, chemical potentials and entrainment matrix in dense homogeneous neutron–proton superfluid mixtures constituting the outer core of neutron stars, are determined fully self-consistently by solving numerically the time-dependent Hartree–Fock–Bogoliubov equations over the whole range of temperatures and flow velocities for which superfluidity can exist. Calculations have been made for npeμ in beta-equilibrium using the Brussels–Montreal functional BSk24. The accuracy of various approximations is assessed and the physical meaning of the different velocities and momentum densities appearing in the theory is clarified. Together with the unified equation of state published earlier, the present results provide consistent microscopic inputs for modeling superfluid neutron-star cores.

scholarly journals ELECTROMAGNETIC EFFECTS IN SUPERCONDUCTORS IN STATIONARY GRAVITATIONAL FIELD

2005 ◽  
Vol 14 (05) ◽  
pp. 837-847 ◽  
Author(s):  
B. J. AHMEDOV ◽  
V. G. KAGRAMANOVA
Keyword(s):  
Gravitational Field ◽  
Magnetic Flux ◽  
Superconducting Devices ◽  
Resistive State ◽  
Superconducting Cylinder ◽  
Inertial Frames ◽  
Radial Heat ◽  
General Relativistic ◽  
Shift Effect ◽  
Stationary Gravitational Field

The general relativistic modifications to the resistive state in superconductors of second type in the presence of a stationary gravitational field are studied. Some superconducting devices that can measure the gravitational field by its red-shift effect on the frequency of radiation are suggested. It has been shown that by varying the orientation of a superconductor with respect to the earth gravitational field, a corresponding varying contribution to AC Josephson frequency would be added by gravity. A magnetic flux (being proportional to angular velocity of rotation Ω) through a rotating hollow superconducting cylinder with the radial gradient of temperature ∇rT is theoretically predicted. The magnetic flux is assumed to be produced by the azimuthal current arising from Coriolis force effect on radial thermoelectric current. Finally the magnetic flux through the superconducting ring with radial heat flow located at the equatorial plane interior of the rotating neutron star is calculated. In particular it has been shown that nonvanishing magnetic flux will be generated due to the general relativistic effect of dragging of inertial frames on the thermoelectric current.

MAGNETIZED ROTATING NEUTRON STARS SIMULATED BY GENERAL-RELATIVISTIC POLYTROPIC MODELS: THE NUMERICAL TREATMENT

2011 ◽  
Vol 22 (10) ◽  
pp. 1107-1137
Author(s):  
V. S. GEROYANNIS ◽  
A. G. KATELOUZOS ◽  
F. N. VALVI
Keyword(s):  
Magnetic Field ◽  
Neutron Stars ◽  
Liouville Problem ◽  
Spherical Shape ◽  
Rotation Periods ◽  
Prolate Shape ◽  
Shafranov Equation ◽  
General Relativistic ◽  
Sturm Liouville ◽  
The Magnetic Field

We compute general-relativistic polytropic models of magnetized rotating neutron stars, assuming that magnetic field and rotation can be treated as decoupled perturbations acting on the nondistorted configuration. Concerning the magnetic field, we develop and apply a numerical method for solving the relativistic Grad–Shafranov equation as a nonhomogeneous Sturm–Liouville problem with nonstandard boundary conditions. We present significant geometrical and physical characteristics of six models, four of which are models of maximum mass. We find negative ellipticities owing to a magnetic field with both toroidal and poloidal components; thus the corresponding configurations have prolate shape. We also compute models of magnetized rotating neutron stars with almost spherical shape due to the counterbalancing of the rotational effect (tending to yield oblate configurations) and the magnetic effect (tending in turn to derive prolate configurations). In this work such models are simply called "equalizers." We emphasize on numerical results related to magnetars, i.e. ultramagnetized neutron stars with relatively long rotation periods.

scholarly journals Vortex pinning in the superfluid core of relativistic neutron stars

2021 ◽  
Vol 503 (1) ◽  
pp. 1407-1417
Author(s):  
Aurélien Sourie ◽  
Nicolas Chamel
Keyword(s):  
Neutron Stars ◽  
Outer Core ◽  
Vortex Pinning ◽  
Global Dynamics ◽  
Mutual Friction ◽  
Dynamical Equations ◽  
General Relativistic ◽  
Superfluid Core ◽  
Relativistic Framework

ABSTRACT Our recent Newtonian treatment of the smooth-averaged mutual-friction force acting on the neutron superfluid and locally induced by the pinning of quantized neutron vortices to proton fluxoids in the outer core of superfluid neutron stars is here adapted to the general-relativistic framework. We show how the local non-relativistic motion of individual vortices can be matched to the global dynamics of the star using the fully 4D covariant Newtonian formalism of Carter & Chamel. We derive all the necessary dynamical equations for carrying out realistic simulations of superfluid rotating neutron stars in full general relativity, as required for the interpretation of pulsar frequency glitches. The role of vortex pinning on the global dynamics appears to be non-trivial.

Quasi-static electric and magnetic fields in vacuum

2018 ◽  
Author(s):  
J. Pierrus
Keyword(s):  
Magnetic Field ◽  
Nineteenth Century ◽  
Magnetic Fields ◽  
Electric Field ◽  
Electromagnetic Induction ◽  
Point Of View ◽  
Time Dependent ◽  
Important Phenomenon ◽  
Electric And Magnetic Fields ◽  
Practical Standpoint

In this chapter, the transition from time-independent to time-dependent source densities and fields is made. It is here that Faraday’s famous nineteenth-century experiments on electromagnetic induction are first encountered. This important phenomenon—whereby a changing magnetic field produces an induced electric field (whose curl is now no longer zero)—forms the basis of most of the questions and solutions which follow. Some new and interesting examples—not usually found in other textbooks—are introduced. These are treated both from an analytical and numerical point of view. Also considered here is the standard yet important topic (at least from a practical standpoint) of mutual and self-inductance. Several questions deal with this concept.

GRACEFUL: Probing the deep Earth interior by synergistic use of observations of the magnetic and gravity fields, and of the rotation of the Earth

2020 ◽  
Author(s):  
Mioara Mandea ◽  
Veronique Dehant ◽  
Anny Cazenave
Keyword(s):  
Magnetic Field ◽  
Gravity Field ◽  
Time Scales ◽  
Earth Rotation ◽  
Outer Core ◽  
Time Dependent ◽  
Mantle Boundary ◽  
Core Mantle Boundary ◽  
The Core ◽  
The Earth

<div> <p>To understand the processes involved in the deep interior of the Earth and explaining its evolution, in particular the dynamics of the Earth’s fluid iron-rich outer core, only indirect satellite and ground observations are available. They each provide invaluable information about the core flow but are incomplete on their own:</p> <p>-        The time dependent magnetic field, originating mainly within the core, can be used to infer the motions of the fluid at the top of the core on decadal and subdecadal time scales.</p> <p>-        The time dependent gravity field variations that reflect changes in the mass distribution within the Earth and at its surface occur on a broad range of time scales. Decadal and interannual variations include the signature of the flow inside the core, though they are largely dominated by surface contributions related to the global water cycle and climate-driven land ice loss.</p> <p>-        Earth rotation changes (or variations in the length of the day) also occur on these time scales, and are largely related to the core fluid motions through exchange of angular momentum between the core and the mantle at the core-mantle boundary.</p> <p>Here, we present the main activities proposed in the frame of the GRACEFUL ERC project, which aims to combine information about the core deduced from the gravity field, from the magnetic field and from the Earth rotation in synergy, in order to examine in unprecedented depth the dynamical processes occurring inside the core and at the core-mantle boundary.</p> </div>

scholarly journals General Relativistic Mean-Field Dynamo Model for Proto-Neutron Stars

Universe ◽  
2020 ◽  
Vol 6 (6) ◽  
pp. 83 ◽  
Author(s):  
Kevin Franceschetti ◽  
Luca Del Zanna
Keyword(s):  
Magnetic Field ◽  
Neutron Stars ◽  
Growth Rates ◽  
Exponential Growth ◽  
Mean Field ◽  
Dynamo Model ◽  
Time Interval ◽  
General Relativistic ◽  
The Magnetic Field ◽  
Mean Field Dynamo

Neutron stars, and magnetars in particular, are known to host the strongest magnetic fields in the Universe. The origin of these strong fields is a matter of controversy. In this preliminary work, via numerical simulations, we study, for the first time in non-ideal general relativistic magnetohydrodynamic (GRMHD) regime, the growth of the magnetic field due to the action of the mean-field dynamo due to sub-scale, unresolved turbulence. The dynamo process, combined with the differential rotation of the (proto-)star, is able to produce an exponential growth of any initial magnetic seed field up to the values required to explain the observations. By varying the dynamo coefficient we obtain different growth rates. We find a quasi-linear dependence of the growth rates on the intensity of the dynamo. Furthermore, the time interval in which exponential growth occurs and the growth rates also seems to depend on the initial configuration of the magnetic field.

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