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Direct numerical simulations of turbulent Hall dynamos are presented. The evolution of an initially weak and small scale magnetic field in a system maintained in a stationary turbulent regime by a stirring force at a macroscopic scale is…

Astrophysics · Physics 2009-11-10 P. D. Mininni , D. O. Gómez , S. M. Mahajan

As another step towards understanding the long-term evolution of the magnetic field in neutron stars, we provide the first simulations of ambipolar diffusion in a spherical star. Restricting ourselves to axial symmetry, we consider a…

High Energy Astrophysical Phenomena · Physics 2017-07-17 F. Castillo , A. Reisenegger , J. A. Valdivia

The evolution of the magnetic field and angular momentum in the collapsing cloud core is studied using three-dimensional resistive MHD nested grid simulations. Starting with a Bonnor-Ebert isothermal cloud rotating in a uniform magnetic…

Astrophysics · Physics 2009-11-13 Masahiro N. Machida , Shu-ichiro Inutsuka , Tomoaki Matsumoto

There are many factors that contribute to the breaking of the spherical symmetry of a neutron star. Most notably is rotation, magnetic fields, and/or accretion of matter from companion stars. All these phenomena influence the macroscopic…

High Energy Astrophysical Phenomena · Physics 2012-05-31 Rodrigo Negreiros , Stefan Schramm , Fridolin Weber

Magnetic fields are known to be dynamically important in the interstellar medium of our own Galaxy, and they are ubiquitously observed in diffuse gas in the halos of galaxies and galaxy clusters. Yet, magnetic fields have typically been…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-05 R. Pakmor , V. Springel

We examine the range of rest-mass densities, temperatures and magnetic fields involved in simulations of binary neutron star mergers (BNSM) and identify the conditions under which the ideal magneto-hydrodynamics (MHD) breaks down using…

High Energy Astrophysical Phenomena · Physics 2019-07-12 Arus S. Harutyunyan

The origin and the magnitude of the inter-galactic magnetic field is of primordial importance in the global picture of magnetic field evolution, as it is considered to be the missing link between galactic magnetic fields and cluster…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Yohan Dubois , Romain Teyssier

We formulate the problem of the late accretion phase of the evolution of an isothermal magnetic disk surrounding a forming star. The evolution is described by the six-fluid MHD equations, accounting for the presence of neutrals, atomic and…

Astrophysics · Physics 2009-11-10 Konstantinos Tassis , Telemachos Ch. Mouschovias

The nonlinear magnetic induction equation with Hall effect can be used to model magnetic fields, e.g. in astrophysical plasma environments. In order to give reliable results, numerical simulations should be carried out using effective and…

Numerical Analysis · Mathematics 2018-10-03 Hendrik Ranocha , Katharina Ostaszewski , Philip Heinisch

We examine the range of rest-mass densities, temperatures and magnetic fields involved in simulations of binary neutron-star mergers and identify the conditions under which the ideal-magnetohydrodynamics approximation breaks down and hence…

High Energy Astrophysical Phenomena · Physics 2018-11-13 Arus Harutyunyan , Antonios Nathanail , Luciano Rezzolla , Armen Sedrakian

(abidged) Context: Stellar convection zones are characterized by vigorous high-Reynolds number turbulence at low Prandtl numbers. Aims: We study the dynamo and differential rotation regimes at varying levels of viscous, thermal, and…

Solar and Stellar Astrophysics · Physics 2017-02-22 P. J. Käpylä , M. J. Käpylä , N. Olspert , J. Warnecke , A. Brandenburg

We consider the evolution of primordial magnetic fields generated during cosmological, electroweak or QCD, phase transitions. We assume that the magnetic field generation can be described as an injection of magnetic energy to cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2013-04-24 Tina Kahniashvili , Alexander G. Tevzadze , Axel Brandenburg , Andrii Neronov

(1) Background: for the study of highly magnetized neutron stars observed as magnetars, and to quantify the effect of this intense magnetic field onto the star's structure and shape which can be particularly relevant for the study of…

High Energy Astrophysical Phenomena · Physics 2026-05-20 Debarati Chatterjee , Daw Guttmann , Jérôme Novak , Micaela Oertel , Martin Jakob Steil

Are the kG-strength magnetic fields observed in young stars a fossil field left over from their formation or are they generated by a dynamo? Our previous numerical study concluded that magnetic fields must originate by a dynamo process.…

Solar and Stellar Astrophysics · Physics 2022-01-20 James Wurster , Matthew R. Bate , Daniel J. Price , Ian A. Bonnell

The impact of the magnetic field on postbounce supernova dynamics of non-rotating stellar cores is studied by performing three-dimensional magnetohydrodynamics simulations with spectral neutrino transport. The explodability of strongly and…

High Energy Astrophysical Phenomena · Physics 2022-08-19 Jin Matsumoto , Yuta Asahina , Tomoya Takiwaki , Kei Kotake , Hiroyuki R. Takahashi

We present an implementation of the Hall term in the non-ideal magnetohydrodynamics equations into the adaptive-mesh-refinement code RAMSES to study its impact on star formation. Recent works show that the Hall effect heavily influences the…

Solar and Stellar Astrophysics · Physics 2018-10-31 Pierre Marchand , Benoît Commerçon , Gilles Chabrier

The generation and evolution of astrophysical magnetic fields occurs largely through the action of turbulence. In many situations, the magnetic field is strong enough to influence many important properties of turbulence itself. Numerical…

Astrophysics · Physics 2007-05-23 Ellen G. Zweibel , Fabian Heitsch , Yuhong Fan

Thermal evolution of neutron stars is studied in the $f(R)=R+\alpha R^{2}$ theory of gravity. We first describe the equations of stellar structure and evolution for a spherically symmetric spacetime plus a perfect fluid at rest. We then…

General Relativity and Quantum Cosmology · Physics 2023-06-08 Martín Nava-Callejas , Dany Page , Mikhail V. Beznogov

This paper intends to give a broad overview of the present knowledge about neutron star magnetic fields, their origin and evolution. An up-to-date overview of the rich phenomenology (encompassing ``classical'' and millisecond radio pulsars,…

Astrophysics · Physics 2007-05-23 Andreas Reisenegger

We present a model of the magnetosphere around an oscillating neutron star. The electromagnetic fields are numerically solved by modeling electric charge and current induced by the stellar torsional mode, with particular emphasis on…

High Energy Astrophysical Phenomena · Physics 2016-06-21 Yasufumi Kojima , Yugo E. Kato