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It is suggested that a set of positive- and negative-energy oscillations can be resonantly excited in the inner region of deformed (warped or eccentric) relativistic disks. In this paper we examine how a dissipative process affects on this…

High Energy Astrophysical Phenomena · Physics 2015-05-27 Shoji Kato

We present an effectively global analytical asymptotic galactic dynamo solution for the regular magnetic field of an axisymmetric thin disc in the saturated state. This solution is constructed by combining two well-known types of local…

Astrophysics of Galaxies · Physics 2016-09-02 Luke Chamandy

This work concentrates on the effect of an irrotational forcing on a magnetized flow in the presence of rotation, baroclinicity, shear, or a combination of them. By including magnetic field in the model we can evaluate the occurrence of…

Astrophysics of Galaxies · Physics 2023-09-08 Albert Elias-López , Fabio Del Sordo , Daniele Viganò

Non-damped oscillations of the magnetization vector of a ferromagnetic system subject to a spin polarized current and an external magnetic field are studied theoretically by solving the Landau-Lifshitz-Gilbert equation. It is shown that the…

Materials Science · Physics 2007-05-23 P. M. Gorley , P. P. Horley , V. K. Dugaev , J. Barnas , V. R. Vieira

Strongly magnetized accretion discs around black holes have attractive features that may explain enigmatic aspects of X-ray binary behaviour. The structure and evolution of these discs are governed by a dynamo-like mechanism, which channels…

High Energy Astrophysical Phenomena · Physics 2016-02-03 Greg Salvesen , Jacob B. Simon , Philip J. Armitage , Mitchell C. Begelman

The formation and evolution of a wide class of astrophysical objects is governed by turbulent, magnetized accretion disks. Understanding their secular dynamics is of primary importance. Apart from enabling mass accretion via the transport…

High Energy Astrophysical Phenomena · Physics 2015-09-16 Oliver Gressel , Martin E. Pessah

Low-mass galaxies radio observations show in many cases surprisingly high levels of magnetic field. The mass and kinematics of such objects do not favour the development of effective large-scale dynamo action. We attempted to check if the…

Astrophysics of Galaxies · Physics 2018-03-14 Hubert Siejkowski , Marian Soida , Krzysztof T. Chyzy

(shortened) Planet forming discs are believed to be very weakly turbulent in the regions outside of 1 AU. For this reason, it is now believed that magnetized winds could be the dominant mechanism driving accretion in these systems. However,…

Solar and Stellar Astrophysics · Physics 2021-06-02 Geoffroy Lesur

We calculate non-axisymmetric oscillations of neutron stars magnetized by purely poloidal magnetic fields. We use polytropes of index $n=1$ and 1.5 as a background model, where we ignore the equilibrium deformation due to the magnetic…

High Energy Astrophysical Phenomena · Physics 2015-12-16 Hidetaka Asai , Umin Lee , Shijun Yoshida

We investigate the dynamical formation of nonlinear patterns in one-dimensional ring condensates under bichromatic periodic modulation of the interaction strength. The stability phase diagram of the condensate's homogeneous density state is…

Quantum Gases · Physics 2025-11-11 Premabrata Manna , S. I. Mistakidis , P. G. Kevrekidis , Pankaj Kumar Mishra

We investigate the classical problem of motion of a mathematical pendulum with an oscillating pivot. This simple mechanical setting is frequently used as the prime example of a system exhibiting the parametric resonance phenomenon, which…

Dynamical Systems · Mathematics 2021-12-30 Dalibor Pražák , Vít Průša , Karel Tůma

Using direct simulations of hydromagnetic turbulence driven by random polarized waves it is shown that dynamo action is possible over a wide range of magnetic Prandtl numbers from 10^-3 to 1. Triply periodic boundary conditions are being…

Astrophysics · Physics 2010-01-15 Axel Brandenburg

The theory of waves and instabilities in a differentially rotating disc containing a poloidal magnetic field is developed within the framework of ideal magnetohydrodynamics. A continuous spectrum, for which the eigenfunctions are localized…

Astrophysics · Physics 2009-10-30 G. I. Ogilvie

In this paper we develop a framework for studying unstratified, magnetised eccentric discs and compute uniformly precessing eccentric modes in a cylindrical annulus which provide convenient initial conditions for numerical simulations. The…

High Energy Astrophysical Phenomena · Physics 2023-09-18 Elliot M. Lynch , Janosz W. Dewberry

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

We consider discs that orbit a central object and are tidally perturbed by a circular orbit companion. Such discs are sometimes subject to an eccentric instability due to the effects of certain resonances. Eccentric instabilities may be…

Solar and Stellar Astrophysics · Physics 2015-05-18 Stephen H. Lubow

We present experimental results of a homopolar disc dynamo constructed at CICATA-Quer\'etaro in Mexico. The device consists of a flat, multi-arm spiral coil which is placed above a fast-spinning metal disc and connected to the latter by…

Geophysics · Physics 2017-03-03 R. A. Avalos-Zúñiga , J. Priede , C. E. Bello-Morales

Magnetic field amplification by a fast dynamo is seen in local box simulations of SN-driven ISM turbulence, where the self-consistent emergence of large-scale fields agrees very well with its mean-field description. We accordingly derive…

Cosmology and Nongalactic Astrophysics · Physics 2012-06-25 Detlef Elstner , Oliver Gressel

Using finite element micromagnetic simulations, we study how resonant magnetisation dynamics in thin magnetic discs with perpendicular anisotropy are influenced by magnetostatic coupling to a magnetic nanoparticle. We identify resonant…

Mesoscale and Nanoscale Physics · Physics 2016-10-12 Maximilian Albert , Marijan Beg , Dmitri Chernyshenko , Marc-Antonio Bisotti , Rebecca L. Carey , Hans Fangohr , Peter J. Metaxas

We investigate the stability of partially ionised, differentially rotating, diffusive disc threaded by both azimuthal and vertical magnetic field. The general stability criterion of such a disc in the presence of axisymmetric fluctuations…

Solar and Stellar Astrophysics · Physics 2015-06-03 B. P. Pandey , Mark Wardle