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Related papers: MRI-driven $\alpha-\Omega$ dynamos in protoneutron…

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We investigate the effects of the magnetic dipole-dipole coupling and the electromagnetic radiation on the frequency evolution of gravitational waves from inspiralling binary neutron stars with magnetic dipole moments. This study is…

Astrophysics · Physics 2009-10-31 Kunihito Ioka , Keisuke Taniguchi

This work looks at some definitive signatures of magnetars, in particular of period closures accompanied by a decline of X-ray radiation in two models. We review some of the previous works which are based on the well known dynamo model in…

High Energy Astrophysical Phenomena · Physics 2018-11-07 Vikram Soni , Dipankar Bhattacharya , Sameer Patel , Sajal Gupta , Prasanta Bera

Some young neutron stars, the magnetars, have ultra-strong magnetic fields, yet their inferred birth rate is comparable to the core-collapse supernova rate, challenging scenarios that require rare, extreme conditions. We propose that this…

High Energy Astrophysical Phenomena · Physics 2026-02-04 İrem Bakır , Kazım Yavuz Ekşi

Differential rotation induced by the r-mode instability can generate very strong toroidal fields in the core of accreting, millisecond spinning neutron stars. We introduce explicitly the magnetic damping term in the evolution equations of…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Carmine Cuofano , Simone Dall'Osso , Alessandro Drago , Luigi Stella

During the first 40 s after their birth, proto-neutron stars are expected to be subject to at least two types of instability: the convective instability and the neutron-finger one. Both instabilities involve convective motions and hence can…

Astrophysics · Physics 2009-06-23 L. Naso , L. Rezzolla , A. Bonanno , L. Paternò

The magnetorotational instability (MRI) may dominate outward transport of angular momentum in accretion disks, allowing material to fall onto the central object. Previous work has established that the MRI can drive a mean-field dynamo,…

Solar and Stellar Astrophysics · Physics 2015-05-27 Jeffrey S. Oishi , Mordecai-Mark Mac Low

The preference for the axial dipole in planetary dynamos is investigated through the analysis of wave motions in spherical dynamo models. Our study focuses on the role of slow magnetostrophic waves, which are generated from localized…

Geophysics · Physics 2022-11-09 Aditya Varma , Binod Sreenivasan

Magneto-elastic oscillations of neutron stars are believed to explain observed quasi-periodic oscillations (QPOs) in the decaying tail of the giant flares of highly magnetized neutron stars (magnetars). Strong efforts of the theoretical…

High Energy Astrophysical Phenomena · Physics 2018-01-10 Michael Gabler , Pablo Cerdá-Durán , Alexei Mate , Nikolaos Stergioulas , José A. Font , Ewald Müller

We present the results of axisymmetric simulations of MRI-driven accretion onto a rapidly rotating, magnetized star accreting in the propeller regime. The stellar magnetosphere corotates with the star, forming a centrifugal barrier at the…

Solar and Stellar Astrophysics · Physics 2015-06-15 Patrick S Lii , Marina M. Romanova , Galina V. Ustyugova , Alexander V. Koldoba , Richard V. E. Lovelace

(abriged) MRI turbulence is a leading mechanism for the generation of an efficient turbulent transport of angular momentum in an accretion disk through a turbulent viscosity effect. It is believed that the same process could also transport…

High Energy Astrophysical Phenomena · Physics 2016-12-07 G. Lesur , P-Y. Longaretti

The magnetorotational instability (MRI) is the leading candidate for driving turbulence, angular momentum transport, and accretion in astrophysical disks. I consider the linear theory of the MRI in a thin, equatorial disk in the Kerr…

Astrophysics · Physics 2009-11-10 Charles F. Gammie

Are magnetic fields important in primordial star formation? Assuming that star formation occurs via an accretion disk that is turbulent, initially because of local gravitational instability, we calculate the disk structure for realistic…

Astrophysics · Physics 2009-11-10 Jonathan C. Tan , Eric G. Blackman

The magnetorotational instability (MRI) is the most promising mechanism by which angular momentum is efficiently transported outwards in astrophysical discs. However, its application to protoplanetary discs remains problematic. These discs…

Earth and Planetary Astrophysics · Physics 2015-06-16 Matthew W. Kunz , Geoffroy Lesur

In the framework of the magnetar model for the Soft Gamma Repeaters and Anomalous X-ray Pulsars, we consider the structure of neutron star magnetospheres threaded by large-scale electrical currents. We construct self-similar, force-free…

Astrophysics · Physics 2007-05-23 M. Lyutikov , C. Thompson , S. R. Kulkarni

Several lines of evidence suggest that protogalactic and galactic environments manage to grow magnetic field very rapidly. This makes the theoretical problem of achieving rapid growth of magnetic fields in such environments difficult.…

Astrophysics · Physics 2009-11-10 D. S. Balsara , J. S. Kim , M. M. Mac Low , G. Mathews

The origin of ultra-intense magnetic fields on magnetars is a mystery in modern astrophysics. We model the core collapse dynamics of massive progenitor stars with high surface magnetic fields in the theoretical framework of a self-similar…

High Energy Astrophysical Phenomena · Physics 2015-05-13 Ren-Yu Hu , Yu-Qing Lou

Nuclear rings at the centers of barred galaxies are known to be strongly magnetized. To explore the effects of magnetic fields on star formation in these rings and nuclear gas flows, we run magnetohydrodynamic simulations in which there is…

Astrophysics of Galaxies · Physics 2023-04-13 Sanghyuk Moon , Woong-Tae Kim , Chang-Goo Kim , Eve C. Ostriker

The light curve of many supernovae (SNe) and gamma-ray bursts (GRBs) can be explained by a sustained injection of extra energy from its possible central engine, a rapidly rotating strongly magnetic neutron star (i.e. magnetar). The magnetic…

High Energy Astrophysical Phenomena · Physics 2016-09-14 Wynn C. G. Ho

We present three-dimensional simulations of the dynamical bar-mode instability in magnetized and differentially rotating stars in full general relativity. Our focus is on the effects that magnetic fields have on the dynamics and the onset…

General Relativity and Quantum Cosmology · Physics 2015-06-16 Luca Franci , Roberto De Pietri , Kyriaki Dionysopoulou , Luciano Rezzolla

Recent asteroseismic analyses have revealed the presence of strong (B $\gtrsim 10^5$ G) magnetic fields in the cores of many red giant stars. Here, we examine the implications of these results for the evolution of stellar magnetic fields,…

Solar and Stellar Astrophysics · Physics 2016-06-15 Matteo Cantiello , Jim Fuller , Lars Bildsten