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

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Magnetars are highly magnetized neutron stars whose magnetic dipole ranges from $10^{14}$ to $10^{15}$ G. The MRI is considered to be a promising mechanism to amplify the magnetic field in fast-rotating protoneutron stars and form…

High Energy Astrophysical Phenomena · Physics 2021-01-27 Alexis Reboul-Salze , Jérôme Guilet , Raphaël Raynaud , Matteo Bugli

Extremely strong magnetic fields of the order of $10^{15}\,{\rm G}$ are required to explain the properties of magnetars, the most magnetic neutron stars. Such a strong magnetic field is expected to play an important role for the dynamics of…

High Energy Astrophysical Phenomena · Physics 2017-10-25 Jerome Guilet , Ewald Mueller , Hans-Thomas Janka , Tomasz Rembiasz , Martin Obergaulinger , Pablo Cerda-Duran , Miguel-Angel Aloy

Magnetohydrodynamic (MHD) turbulence is of key importance in many high-energy astrophysical systems, where MHD instabilities can amplify local magnetic field over very short time scales. Specifically, the magnetorotational instability (MRI)…

High Energy Astrophysical Phenomena · Physics 2018-03-30 Philipp Mösta , Christian D. Ott , David Radice , Luke F. Roberts , Erik Schnetter , Roland Haas

The magneto-rotational instability (MRI) is considered to be a promising mechanism to amplify the magnetic field in fast rotating protoneutron stars. In contrast to accretion disks, radial buoyancy driven by entropy and lepton fraction…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Jerome Guilet , Ewald Mueller

The magnetorotational instability (MRI) is a promising mechanism to amplify the magnetic field in fast rotating protoneutron stars. The diffusion of neutrinos trapped in the PNS induces a transport of momentum, which can be modelled as a…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Jerome Guilet , Ewald Mueller , Hans-Thomas Janka

To power gamma-ray bursts and other high-energy events, large-scale magnetic fields are required to extract rotational energy from compact objects such as black holes and neutron stars. The magnetorotational instability (MRI) is a key…

High Energy Astrophysical Phenomena · Physics 2025-09-17 Alexis Reboul-Salze , Loren E. Held , Kenta Kiuchi

The release of spin-down energy by a magnetar is a promising scenario to power several classes of extreme explosive transients. However, it lacks a firm basis because magnetar formation still represents a theoretical challenge. Using the…

High Energy Astrophysical Phenomena · Physics 2020-03-17 Raphaël Raynaud , Jérôme Guilet , Hans-Thomas Janka , Thomas Gastine

Magnetorotational instability (MRI) has been suggested to lead a rapid growth of the magnetic field in core collapse supernovae and produce departures from spherical syymmetry that can be important in determining the explosion mechanism. We…

Solar and Stellar Astrophysics · Physics 2015-05-14 V. Urpin

Magnetorotational instability (MRI) in a convectively-stable layer around the neutrinosphere is simulated by a three-dimensional model of supernova core. To resolve MRI-unstable modes, a thin layer approximation considering only the radial…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Youhei Masada , Tomoya Takiwaki , Kei Kotake

The dynamo driven by the magnetorotational instability (MRI) is believed to play an important role in the dynamics of accretion discs and may also explain the origin of the extreme magnetic fields present in magnetars. Its saturation level…

High Energy Astrophysical Phenomena · Physics 2022-09-21 Jerome Guilet , Alexis Reboul-Salze , Raphael Raynaud , Matteo Bugli , Basile Gallet

We discuss results of global 3D MHD simulations of accretion on to a rotating magnetized star with a tilted dipole magnetic field, where the accretion is driven by the magneto-rotational instability (MRI). The simulations show that…

Solar and Stellar Astrophysics · Physics 2015-06-03 M. M. Romanova , G. V. Ustyugova , A. V. Koldoba , R. V. E. Lovelace

The merger of two neutron stars may give birth to a long-lived hypermassive neutron star. If it harbours a strong magnetic field of magnetar strength, its spin-down could explain several features of short gamma-ray burst afterglows. The…

High Energy Astrophysical Phenomena · Physics 2017-08-23 Jerome Guilet , Andreas Bauswein , Oliver Just , Hans-Thomas Janka

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

We briefly review the turbulent mean-field dynamo action in protoneutron stars that are subject to convective and neutron finger instabilities during the early evolutionary phase. By solving the mean-field induction equation with the…

High Energy Astrophysical Phenomena · Physics 2011-01-11 Alfio Bonanno , Vadim Urpin

The discovery of the first binary neutron star merger, GW170817, has spawned a plethora of global numerical relativity simulations. These simulations are often ideal (with dissipation determined by the grid) and/or axisymmetric (invoking ad…

High Energy Astrophysical Phenomena · Physics 2024-04-10 Loren E. Held , George Mamatsashvili , Martin E. Pessah

We discuss the mean-field dynamo action in protoneutron stars that are subject to instabilities during the early evolutionary phase. The mean field is generated in the neutron-finger unstable region where the Rossby number is $\sim 1$ and…

Astrophysics · Physics 2009-11-11 A. Bonanno , V. Urpin , G. Belvedere

Neutrino radiation takes a major role in the momentum, heat, and lepton transports in proto-neutron stars (PNSs). These diffusive processes affect the growth of magnetorotational instability (MRI) in PNSs. We perform a local linear analysis…

Astrophysics · Physics 2008-11-26 Youhei Masada , Takayoshi Sano , Kazunari Shibata

Stellar magnetism plays an important role in stellar evolution theory. Approximatively 10% of observed main sequence (MS) and pre-main-sequence (PMS) radiative stars exhibit surface magnetic fields above the detection limit, raising the…

Solar and Stellar Astrophysics · Physics 2018-01-24 Jérémie Vidal , David Cébron , Nathanaël Schaeffer , Rainer Hollerbach

Spectropolarimetric observations show that many low-mass stars possess large-scale poloidal magnetic fields with considerable dipole component, which in some cases exhibit temporal dynamics - cycles or reversals. Although it is widely…

Solar and Stellar Astrophysics · Physics 2025-07-02 Anna Guseva , Ludovic Petitdemange , Charly Pinçon

The origin of large-scale and coherent magnetic fields in astrophysical discs is an important and long standing problem. Researchers commonly appeal to a turbulent dynamo, sustained by the magneto-rotational instability (MRI), to supply the…

High Energy Astrophysical Phenomena · Physics 2018-10-24 A. Riols , H. Latter
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