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The hydromagnetic structure of a neutron star accreting symmetrically at both magnetic poles is calculated as a function of accreted mass, M_a, and polar cap radius,starting from a centered magnetic dipole and evolving through a quasistatic…

Astrophysics · Physics 2009-11-10 D. J. B. Payne , A. Melatos

We study the stability of neutron stars with toroidal magnetic fields by magnetohydrodynamic simulation in full general relativity under assumption of axial symmetry. Nonrotating and rigidly rotating neutron stars are prepared for a variety…

Astrophysics · Physics 2008-12-18 Kenta Kiuchi , Masaru Shibata , Shijun Yoshida

We calculate axisymmetric oscillations of rotating neutron stars composed of the surface fluid ocean, solid crust, and fluid core, taking account of a dipole magnetic field as strong as $B_S\sim 10^{15}$G at the surface. The adiabatic…

Astrophysics · Physics 2008-11-26 Umin Lee

A method is proposed to solve the Grad-Shafranov partial differential equation for the poloidal flux function associated with the equilibrium of a plasma magnetically confined in an axisymmetric torus under the assumption that the sources…

Plasma Physics · Physics 2018-09-06 Antonio Carlos de Almeida Ferreira

We extend our previous study of equilibrium solutions of non-rotating force-free magnetospheres of neutron stars. We show that multiple solutions exist for the same sets of parameters, implying that the solutions are degenerate. We are able…

High Energy Astrophysical Phenomena · Physics 2018-10-11 Taner Akgün , Pablo Cerdá-Durán , Juan Antonio Miralles , José A. Pons

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…

High Energy Astrophysical Phenomena · Physics 2022-01-24 Konstantinos N. Gourgouliatos , Davide De Grandis , Andrei Igoshev

We have numerically solved the Grad-Shafranov equation for axisymmetric static MHD equilibria of matter confined at the polar cap of neutron stars. From the equilibrium solutions we explore the stability of the accretion mounds using the…

High Energy Astrophysical Phenomena · Physics 2013-05-14 Dipanjan Mukherjee , Dipankar Bhattacharya , Andrea Mignone

Although barotropic matter does not constitute a realistic model for magnetic stars, it would be interesting to confirm a recent conjecture that states that magnetized stars with a barotropic equation of state would be dynamically unstable…

Solar and Stellar Astrophysics · Physics 2015-06-15 Cristobal Armaza , Andreas Reisenegger , Juan Alejandro Valdivia , Pablo Marchant

We obtained the magnetic field configurations, including both poloidal and toroidal components, throughout the interior and exterior of magnetars using a realistic equation of state. We divided the magnetized star into the hydromagnetic…

High Energy Astrophysical Phenomena · Physics 2015-10-01 Kotaro Fujisawa , Shota Kisaka

Following the general formalism presented by Rezzolla, Ahmedov and Miller (MNRAS, 322, 723 2001), we here derive analytic solutions of the electromagnetic fields equations in the internal and external background spacetime of a slowly…

General Relativity and Quantum Cosmology · Physics 2007-05-23 L. Rezzolla , B. J. Ahmedov , J. C. Miller

We investigate the effects of the purely toroidal magnetic field on the equilibrium structures of the relativistic stars. The master equations for obtaining equilibrium solutions of relativistic rotating stars containing purely toroidal…

Astrophysics · Physics 2008-11-26 Kenta Kiuchi , Shijun Yoshida

In this work we explore the evolution of magnetic fields inside strongly magnetized neutron stars in axisymmetry. We model numerically the coupled field evolution in the core and the crust. Our code models the Hall drift and Ohmic effects…

High Energy Astrophysical Phenomena · Physics 2017-11-29 Ashley Bransgrove , Yuri Levin , Andrei Beloborodov

Vlasov equilibria of axisymmetric plasmas with vacuum toroidal magnetic field can be reduced, up to a selection of ions and electrons distributions functions, to a Grad-Shafranov-like equation. Quasineutrality narrow the choice of the…

Plasma Physics · Physics 2015-06-18 H. Tasso , G. N. Throumoulopoulos

In a previous paper, we reported simulations of the evolution of the magnetic field in neutron star cores through ambipolar diffusion, taking the neutrons as a motionless uniform background. However, in real neutron stars, neutrons are free…

High Energy Astrophysical Phenomena · Physics 2020-09-02 F. Castillo , A. Reisenegger , J. A. Valdivia

The phenomenology of the emission of pulsars and magnetars depends dramatically on the structure and properties of their magnetic field. In particular it is believed that the outbursting and flaring activity observed in AXPs and SRGs is…

High Energy Astrophysical Phenomena · Physics 2016-06-22 N. Bucciantini , A. G. Pili , L. Del Zanna

This work presents a global solution for the internal and the external field of an axisymmetric rotating neutron star. It is shown that the twist of the internal field affects the external field, by increasing the number of open field lines…

High Energy Astrophysical Phenomena · Physics 2025-08-13 D. Ntotsikas , K. N. Gourgouliatos

The evolution of the magnetic field in neutron star crusts because of the Hall effect has received significant attention over the last two decades, which is strongly justified because of the dominance of this effect in highly magnetised…

High Energy Astrophysical Phenomena · Physics 2023-03-15 Konstantinos N. Gourgouliatos

Context. The understanding of fossil fields origin, topology and stability is one of the corner stones of the stellar magnetism theory. On one hand, since they survive over secular time-scales, they may modify the structure and the…

Solar and Stellar Astrophysics · Physics 2010-03-16 V. Duez , S. Mathis

Soft Gamma-Ray Repeaters and Anomalous X-Ray Pulsars are extreme manifestations of the most magnetized neutron stars: magnetars. The phenomenology of their emission and spectral properties strongly support the idea that the magnetospheres…

High Energy Astrophysical Phenomena · Physics 2015-06-23 A. G. Pili , N. Bucciantini , L. Del Zanna

Aims. In the first few minutes of a newborn neutron star's life the Hall effect and differential rotation may both be important. We demonstrate that these two ingredients are sufficient for generating a 'shear-Hall instability' and for…

Solar and Stellar Astrophysics · Physics 2011-11-15 Todor Kondić , Günther Rüdiger , Rainer Hollerbach