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Current "Earth-like" numerical dynamo simulations are able to reproduce many characteristics of the observed geomagnetic field. One notable exception is the geomagnetic octupolar component. Here we investigate whether a stably stratified…

Geophysics · Physics 2018-10-11 Chi Yan , Sabine Stanley

The planets magnetic field has been explained based on the dynamo theory, which presents as many difficulties in mathematical terms as well as in predictions. It proves to be extremely difficult to calculate the dipolar magnetic moment of…

Earth and Planetary Astrophysics · Physics 2016-07-04 Hector Javier Durand-Manterola

Cosmological simulations of magnetic fields in galaxy clusters show that remarkable agreement between simulations and observations of Faraday rotation and radio haloes can be achieved assuming that seed fields of 10^{-9} G were present at…

Astrophysics · Physics 2007-05-23 Matthias Bartelmann , Klaus Dolag , Harald Lesch

Disc accretion to a rotating star with a non-dipole magnetic field is investigated for the first time in full three-dimensional (3D) magnetohydrodynamic (MHD) simulations. We investigated the cases of (1) pure dipole, (2) pure quadrupole,…

Astrophysics · Physics 2008-11-26 M. Long , M. M. Romanova , R. V. E. Lovelace

Models of rotating relativistic stars with a toroidal magnetic field have been computed for a sample of eight equations of state of cold dense matter. Non-rotating models admit important levels of magnetization and quadrupole distortion…

General Relativity and Quantum Cosmology · Physics 2015-06-18 Joachim Frieben , Luciano Rezzolla

The magnetic field within a few hundred parsecs of the center of the Galaxy is an essential component of any description of that region. The field has several pronounced observational manifestations: 1) morphological structures such as…

Astrophysics · Physics 2007-05-23 Mark Morris

We describe the construction of a prototype hybrid permanent magnet dipole and quadruple. The magnet consists of two concentric rings of SmCo magnetic material 5 cm in length. The outer ring is made of 16 uniformly magnetized blocks…

Accelerator Physics · Physics 2008-11-26 M. Sullivan , G. Bowden , S. Ecklund , D. Jensen , M. Nordby , A. Ringwall , Z. R. Wolf

The structure of an interior dipole magnetic field of neutron stars in $f(R)$ gravity is considered. For this purpose, the perturbative approaches are used when both the deviations from general relativity and the deformations of spherically…

General Relativity and Quantum Cosmology · Physics 2016-09-21 Elizat Bakirova , Vladimir Folomeev

A new static and azimuthally symmetric magnetic monopolelike object, which looks like a Dirac monopole when seen from far away but smoothly changes to a dipole near the monopole position and vanishes at the origin, is discussed. This…

High Energy Physics - Theory · Physics 2020-03-18 Shinichi Deguchi , Kazuo Fujikawa

In order to address the generation of neutron star magnetic fields, with particular focus on the dichotomy between magnetars and radio pulsars, we consider the properties of dynamos as inferred from other astrophysical systems. With…

High Energy Astrophysical Phenomena · Physics 2022-02-23 Christopher J. White , Adam Burrows , Matthew S. B. Coleman , David Vartanyan

Multipoles are paramount for describing electromagnetic fields in many areas of nanoscale optics, playing an essential role for the design of devices in plasmonics and all-dielectric nanophotonics. Challenging the traditional division into…

It is well known that a closed loop of magnetic dipoles can give rise to the rather elusive toroidal moment. However, artificial structures required to generate the necessary magnetic moments are typically optically large, complex to make…

Optics · Physics 2017-01-11 Hong Xiang , Lixin Ge , Liang Liu , Tianshu Jiang , Z. Q. Zhang , C. T. Chan , Dezhuan Han

The polarization data of the radio galaxy NGC4869, belonging to the Coma cluster and located in its central region, allow us to obtain information on the structure of magnetic field associated with the cluster itself. A magnetic field of…

Astrophysics · Physics 2008-02-03 L. Feretti , D. Dallacasa , G. Giovannini , A. Tagliani

We present the first statistical study of magnetic structures and associated energy dissipation observed during a single period of turbulent magnetic reconnection, by using the \textit{in-situ} measurements of the Magnetospheric Multiscale…

Space Physics · Physics 2020-10-28 K. Bergstedt , H. Ji , J. Jara-Almonte , J. Yoo , R. E. Ergun , L. -J. Chen

A thermodynamic model for the generation of magnetic fields in the planets is proposed, considering crossed effects between gravitational and electric forces. The magnetic field of the Earth is estimated and found to be in agreement with…

Astrophysics · Physics 2007-05-23 F. X. Alvarez

We initiate numerical studies of differentially rotating magnetised (proto) neutron stars by studying - through construction from first principles - the coupling between an assumed differential rotation and an impressed magnetic field. For…

Astrophysics · Physics 2007-05-23 A. V. Thampan

The current density of a moving electric dipole is expressed as the sum of polarization and magnetization currents. The magnetic field due to the latter current is that of a magnetic dipole moment that is consistent with the relativistic…

Classical Physics · Physics 2015-06-03 V. Hnizdo

We consider the Dirichlet Laplacian with a constant magnetic field in a two-dimensional domain of finite measure. We determine the sharp constants in semi-classical eigenvalue estimates and show, in particular, that Polya's conjecture is…

Mathematical Physics · Physics 2007-10-05 Rupert L. Frank , Michael Loss , Timo Weidl

The cluster multipole (CMP) expansion for magnetic structures provides a scheme to systematically generate candidate magnetic structures specifically including noncollinear magnetic configurations adapted to the crystal symmetry of a given…

Materials Science · Physics 2021-02-19 Marie-Therese Huebsch , Takuya Nomoto , Michi-To Suzuki , Ryotaro Arita

Optical spectropolarimeters can be used to produce maps of the surface magnetic fields of stars and hence to determine how stellar magnetic fields vary with stellar mass, rotation rate, and evolutionary stage. In particular, we now can map…

Solar and Stellar Astrophysics · Physics 2015-05-20 S. G. Gregory