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We performed 2D and full 3D magnetohydrodynamic simulations of disk accretion to a rotating star with an aligned or misaligned dipole magnetic field. We investigated the rotational equilibrium state and derived from simulations the ratio…

We present results of 2D and 3D PIC simulations of magnetic turbulence production by isotropic cosmic-ray ions drifting upstream of SNR shocks. The studies aim at testing recent predictions of a strong amplification of short wavelength…

Astrophysics · Physics 2009-11-13 Jacek Niemiec , Martin Pohl , Thomas Stroman , and Ken-Ichi Nishikawa

We perform numerical simulations of magneto-rotational instability in a local patch of accretion disk in which radiation pressure exceeds gas pressure. Such conditions may occur in the central regions of disks surrounding compact objects in…

Astrophysics · Physics 2007-05-23 N. J. Turner , J. M. Stone , T. Sano

In stably stratified stars, numerical magneto-hydrodynamics simulations have shown that arbitrary initial magnetic fields evolve into stable equilibrium configurations, usually containing nearly axisymmetric, linked poloidal and toroidal…

Solar and Stellar Astrophysics · Physics 2015-06-23 J. P. Mitchell , J. Braithwaite , A. Reisenegger , H. Spruit , J. A. Valdivia , N. Langer

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 effect of magnetic field diffusion on the stability of accretion disks is a problem that has attracted considerable interest of late. In particular, the Hall effect has the potential to bring about remarkable changes in the dynamical…

Earth and Planetary Astrophysics · Physics 2017-03-29 Gopakumar Mohandas , Martin E. Pessah

In dilute astrophysical plasmas, the collisional mean free path of a particle can exceed its Larmor radius. Under these conditions, the thermal conductivity and viscosity of the plasma can be dramatically altered. This alteration allows…

Astrophysics · Physics 2009-11-11 Tanim Islam , Steven Balbus

We investigate the evolution of hydromagnetic perturbations in a small section of accretion disks. It is known that molecular viscosity is negligible in accretion disks. Hence, it has been argued that Magnetorotational Instability (MRI) is…

High Energy Astrophysical Phenomena · Physics 2016-03-02 Sujit K. Nath , Banibrata Mukhopadhyay

Tayler instability of toroidal magnetic fields $B_\phi$ is broadly invoked as a trigger for turbulence and angular momentum transport in stars. This paper presents a systematic revision of the linear stability analysis for a rotating,…

Solar and Stellar Astrophysics · Physics 2024-10-29 Valentin A. Skoutnev , Andrei M. Beloborodov

The amplification of a magnetic field due to the Richtmyer-Meshkov instability (RMI) is investigated by two-dimensional MHD simulations. Single-mode analysis is adopted to reveal definite relation between the nonlinear evolution of RMI and…

High Energy Astrophysical Phenomena · Physics 2015-06-11 Takayoshi Sano , Katsunobu Nishihara , Chihiro Matsuoka , Tsuyoshi Inoue

Aims. We investigate the cosmological evolution of large- and small-scale magnetic fields in galaxies in the light of present models of formation and evolution of galaxies. Methods. We use the dynamo theory to derive the timescales of…

Astrophysics · Physics 2009-11-13 Tigran G. Arshakian , Rainer Beck , Marita Krause , Dmitry Sokoloff

Using local 3D MHD simulations, we investigate ways in which galactic turbulence associated with the magnetorotational instability (MRI) may influence the formation and properties of GMCs. Our disk models are vertically stratified and…

Astrophysics · Physics 2009-11-10 Woong-Tae Kim , Eve C. Ostriker , James M. Stone

We investigate the stability of the Hall-MHD system and determine its importance for neutron stars at their birth, when they still consist of differentially rotating plasma permeated by extremely strong magnetic fields. We solve the…

Solar and Stellar Astrophysics · Physics 2015-06-04 T. Kondic , G. Ruediger , R. Arlt

Magnetorotational instability (MRI) is the most promising mechanism behind accretion in low-mass protostellar disks. Here we present the first analysis of the global structure and evolution of non-ideal MRI-driven T-Tauri disks on…

Earth and Planetary Astrophysics · Physics 2015-06-15 Russell Landry , Sarah E. Dodson-Robinson , Neal J. Turner , Greg Abram

In addition to buoyancy- and magnetic tension-driven instabilities, magnetic flux rings are also susceptible to an instability induced by the hydrodynamic drag force. We investigate the influence of the toroidal shape and equilibrium…

Astrophysics · Physics 2009-11-13 Volkmar Holzwarth

The evolution of the magnetic field from the large-scale dynamo is considered a central feature of the accretion disk around a black hole. The resulting low-frequency oscillations introduced from the growth and decay of the field strength,…

High Energy Astrophysical Phenomena · Physics 2018-07-11 J. Drew Hogg , Christopher Reynolds

The chiral magnetic effect emerges from a miroscopic level, and its interesting consequences have been discussed in the dynamics of the early universe, neutron stars and quark-gluon plasma. An instability is caused by anomalous electric…

High Energy Astrophysical Phenomena · Physics 2019-03-01 Yasufumi Kojima , Yuri Miura

We study the effects of anisotropic thermal conduction on low-collisionality, astrophysical plasmas using two and three-dimensional magnetohydrodynamic simulations. For weak magnetic fields, dilute plasmas are buoyantly unstable for either…

Cosmology and Nongalactic Astrophysics · Physics 2012-12-05 Michael McCourt , Ian J. Parrish , Prateek Sharma , Eliot Quataert

Using an isothermal MHD code, we have performed three-dimensional, high-resolution simulations of the Parker instability. The initial equilibrium system is composed of exponentially-decreasing isothermal gas and magnetic field (along the…

Astrophysics · Physics 2009-10-30 Jongsoo Kim , S. S. Hong , Dongsu Ryu , T. W. Jones

We study local radiation magnetohydrodynamic instabilities in static, optically thick, vertically stratified media with constant flux mean opacity. We include the effects of vertical gradients in a horizontal background magnetic field.…

High Energy Astrophysical Phenomena · Physics 2015-05-30 Ted Tao , Omer Blaes