scholarly journals CURRENT DRIVEN KINK INSTABILITY IN A MAGNETICALLY DOMINATED ROTATING RELATIVISTIC JET

2014 ◽  
Vol 28 ◽  
pp. 1460201 ◽  
Author(s):  
YOSUKE MIZUNO ◽  
KEN-ICHI NISHIKAWA ◽  
YURI LYUBARSKY ◽  
PHILIP E. HARDEE
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Three Dimensional ◽  
Temporal Development ◽  
Differential Motion ◽  
Relativistic Jet ◽  
Linear And Nonlinear ◽  
Magnetohydrodynamic Simulations ◽  
Kink Instability ◽  
Helical Magnetic Field

We have investigated the influence of jet rotation and differential motion on the linear and nonlinear development of the current-driven (CD) kink instability of force-free helical magnetic equilibria via three-dimensional relativistic magnetohydrodynamic simulations. In this study, we follow the temporal development within a periodic computational box. Displacement of the initial helical magnetic field leads to the growth of the CD kink instability. In the rotating relativistic jet case, developing helical kink structure propagates along jet as it grows in amplitude. The growth rate of the CD kink instability does not depend on the jet rotation. The coupling of multiple unstable wavelengths is crucial to determining whether the jet is eventually disrupted in the nonlinear stage. The CD kink instability deformed magnetic field may trigger magnetic reconnection in the jet.

MAGNETIC COLLIMATION AND MAGNETOHYDRODYNAMIC KINK INSTABILITY DRIVEN BY DIFFERENTIAL ROTATION

2008 ◽  
Vol 17 (10) ◽  
pp. 1707-1713 ◽  
Author(s):  
C. S. CAREY ◽  
C. R. SOVINEC ◽  
S. HEINZ ◽  
J. E. EVERETT
Keyword(s):  
Growth Rate ◽  
Accretion Disk ◽  
Differential Rotation ◽  
Rotation Rate ◽  
Three Dimensional ◽  
Small Scale ◽  
Two Dimensional ◽  
Extragalactic Jets ◽  
Magnetohydrodynamic Simulations ◽  
Kink Instability

We investigate the launching and stability of extragalactic jets through magnetohydrodynamic simulations of jet evolution. In these simulations, a small scale equilibrium magnetic corona is twisted by a differentially rotating accretion disk. Two-dimensional calculations show the formation of a collimated outflow. This outflow is divided into two regions by the Alfvén surface: a magnetically dominated Poynting region, and a kinetically dominated region. Three-dimensional calculations show that the outflow is unstable to the m = 1 kink instability, and that the growth rate of the kink instability decreases as the rotation rate of the accretion disk increases.

scholarly journals Three-dimensional simulations of solar magneto-convection including effects of partial ionization

2018 ◽  
Vol 618 ◽  
pp. A87 ◽  
Author(s):  
E. Khomenko ◽  
N. Vitas ◽  
M. Collados ◽  
A. de Vicente
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Ambipolar Diffusion ◽  
Solar Chromosphere ◽  
Degree Of Ionization ◽  
Poynting Flux ◽  
Complex Interactions ◽  
Low Degree ◽  
Magnetohydrodynamic Simulations ◽  
Three Dimensional Simulations

In recent decades, REALISTIC three-dimensional radiative-magnetohydrodynamic simulations have become the dominant theoretical tool for understanding the complex interactions between the plasma and magnetic field on the Sun. Most of such simulations are based on approximations of magnetohydrodynamics, without directly considering the consequences of the very low degree of ionization of the solar plasma in the photosphere and bottom chromosphere. The presence of a large amount of neutrals leads to a partial decoupling of the plasma and magnetic field. As a consequence, a series of non-ideal effects, i.e., the ambipolar diffusion, Hall effect, and battery effect, arise. The ambipolar effect is the dominant in the solar chromosphere. We report on the first three-dimensional realistic simulations of magneto-convection including ambipolar diffusion and battery effects. The simulations are carried out using the newly developed MANCHA3Dcode. Our results reveal that ambipolar diffusion causes measurable effects on the amplitudes of waves excited by convection in the simulations, on the absorption of Poynting flux and heating, and on the formation of chromospheric structures. We provide a low limit on the chromospheric temperature increase owing to the ambipolar effect using the simulations with battery-excited dynamo fields.

scholarly journals Magnetic field generation in a jet-sheath plasma via the kinetic Kelvin-Helmholtz instability

2013 ◽  
Vol 31 (9) ◽  
pp. 1535-1541 ◽  
Author(s):  
K.-I. Nishikawa ◽  
P. Hardee ◽  
B. Zhang ◽  
I. Duţan ◽  
M. Medvedev ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Magnetic Fields ◽  
Electric Field ◽  
Flow Direction ◽  
Transverse Magnetic ◽  
Velocity Shear ◽  
Helmholtz Instability ◽  
Magnetic Field Generation ◽  
Relativistic Jet

Abstract. We have investigated the generation of magnetic fields associated with velocity shear between an unmagnetized relativistic jet and an unmagnetized sheath plasma. We have examined the strong magnetic fields generated by kinetic shear (Kelvin–Helmholtz) instabilities. Compared to the previous studies using counter-streaming performed by Alves et al. (2012), the structure of the kinetic Kelvin–Helmholtz instability (KKHI) of our jet-sheath configuration is slightly different, even for the global evolution of the strong transverse magnetic field. In our simulations the major components of growing modes are the electric field Ez, perpendicular to the flow boundary, and the magnetic field By, transverse to the flow direction. After the By component is excited, an induced electric field Ex, parallel to the flow direction, becomes significant. However, other field components remain small. We find that the structure and growth rate of KKHI with mass ratios mi/me = 1836 and mi/me = 20 are similar. In our simulations saturation in the nonlinear stage is not as clear as in counter-streaming cases. The growth rate for a mildly-relativistic jet case (γj = 1.5) is larger than for a relativistic jet case (γj = 15).

scholarly journals Filaments and striations: anisotropies in observed, supersonic, highly magnetized turbulent clouds

2019 ◽  
Vol 492 (1) ◽  
pp. 668-685 ◽  
Author(s):  
James R Beattie ◽  
Christoph Federrath
Keyword(s):  
Magnetic Field ◽  
Column Density ◽  
Three Dimensional ◽  
High Density ◽  
Systematic Analysis ◽  
Guide Field ◽  
Degree Of Anisotropy ◽  
Mach Numbers ◽  
Magnetohydrodynamic Simulations ◽  
The Magnetic Field

ABSTRACT Stars form in highly magnetized, supersonic turbulent molecular clouds. Many of the tools and models that we use to carry out star formation studies rely upon the assumption of cloud isotropy. However, structures like high-density filaments in the presence of magnetic fields and magnetosonic striations introduce anisotropies into the cloud. In this study, we use the two-dimensional power spectrum to perform a systematic analysis of the anisotropies in the column density for a range of Alfvén Mach numbers ($\operatorname{\mathcal {M}_{\text{A}}}=0.1{\!-\!10}$) and turbulent Mach numbers ($\operatorname{\mathcal {M}}=2{\!-\!20}$), with 20 high-resolution, three-dimensional turbulent magnetohydrodynamic simulations. We find that for cases with a strong magnetic guide field, corresponding to $\operatorname{\mathcal {M}_{\text{A}}}\lt 1$, and $\operatorname{\mathcal {M}}\lesssim 4$, the anisotropy in the column density is dominated by thin striations aligned with the magnetic field, while for $\operatorname{\mathcal {M}}\gtrsim 4$ the anisotropy is significantly changed by high-density filaments that form perpendicular to the magnetic guide field. Indeed, the strength of the magnetic field controls the degree of anisotropy and whether or not any anisotropy is present, but it is the turbulent motions controlled by $\operatorname{\mathcal {M}}$ that determine which kind of anisotropy dominates the morphology of a cloud.

scholarly journals Colliding-Wind Binaries as a Source of TeV Cosmic Rays

2021 ◽  
Vol 8 ◽  
Author(s):  
Grzegorz Kowal ◽  
Diego A. Falceta-Gonçalves
Keyword(s):  
Magnetic Field ◽  
Gamma Ray ◽  
Three Dimensional ◽  
Strong Shock ◽  
Compact Object ◽  
High Energy ◽  
Test Particles ◽  
Very High Energy ◽  
Magnetohydrodynamic Simulations ◽  
Very High

In addition to gamma-ray binaries which contain a compact object, high-energy and very high–energy gamma rays have also been detected from colliding-wind binaries. The collision of the winds produces two strong shock fronts, one for each wind, both surrounding a shock region of compressed and heated plasma, where particles are accelerated to very high energies. Magnetic field is also amplified in the shocked region on which the acceleration of particles greatly depends. In this work, we performed full three-dimensional magnetohydrodynamic simulations of colliding winds coupled to a code that evolves the kinematics of passive charged test particles subject to the plasma fluctuations. After the run of a large ensemble of test particles with initial thermal distributions, we show that such shocks produce a nonthermal population (nearly 1% of total particles) of few tens of GeVs up to few TeVs, depending on the initial magnetization level of the stellar winds. We were able to determine the loci of fastest acceleration, in the range of MeV/s to GeV/s, to be related to the turbulent plasma with amplified magnetic field of the shock. These results show that colliding-wind binaries are indeed able to produce a significant population of high-energy particles, in relatively short timescales, compared to the dynamical and diffusion timescales.

scholarly journals Linear and Nonlinear Convection with an Aligned Magnetic Field

1990 ◽  
Vol 142 ◽  
pp. 135-136
Author(s):  
N. Rudraiah ◽  
I S Shivakumara ◽  
P Geetavani
Keyword(s):  
Magnetic Field ◽  
Fluid Layer ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Horizontal Magnetic Field ◽  
Nonlinear Convection ◽  
Linear And Nonlinear ◽  
Horizontal Fluid Layer ◽  
Aligned Magnetic Field

The effect of horizontal magnetic field on the onset of three-dimensional convection in a horizontal fluid layer is studied. It is found that the two-dimensional solutions are unstable to three-dimensional disturbances. A detailed bifurcation study is reported.

Pseudo-three-dimensional convective cell motion in a magnetized plasma

1984 ◽  
Vol 31 (2) ◽  
pp. 231-238 ◽  
Author(s):  
P. K. Shukla ◽  
M. Y. Yu
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Mode Coupling ◽  
Three Dimensional ◽  
Convective Cell ◽  
Magnetized Plasma ◽  
Space Plasmas ◽  
Linear And Nonlinear ◽  
Convective Cells ◽  
Cell Motion

Linear and nonlinear mechanisms for generating convective cells with finite but small parallel (to the external magnetic field B0) wavelength are presented. The problems of mode-coupling as well as quasi-steady nonlinear mode structures are analytically studied. Possible applications in space plasmas are discussed.

scholarly journals Magnetic inhibition of the recollimation instability in relativistic jets

2021 ◽  
Vol 503 (4) ◽  
pp. 4918-4929
Author(s):  
Jin Matsumoto ◽  
Serguei S Komissarov ◽  
Konstantinos N Gourgouliatos
Keyword(s):  
Magnetic Field ◽  
Active Galactic Nuclei ◽  
Three Dimensional ◽  
Galactic Nuclei ◽  
Rotating Fluids ◽  
Relativistic Jets ◽  
Azimuthal Magnetic Field ◽  
Centrifugal Instability ◽  
Magnetohydrodynamic Simulations

ABSTRACT In this paper, we describe the results of three-dimensional relativistic magnetohydrodynamic simulations aimed at probing the role of regular magnetic field on the development of the instability that accompanies recollimation of relativistic jets. In particular, we studied the recollimation driven by the reconfinement of jets from active galactic nuclei (AGN) by the thermal pressure of galactic coronas. We find that a relatively weak azimuthal magnetic field can completely suppress the recollimation instability in such jets, with the critical magnetization parameter σcr < 0.01. We argue that the recollimation instability is a variant of the centrifugal instability (CFI) and show that our results are consistent with the predictions based on the study of magnetic CFI in rotating fluids. The results are discussed in the context of AGN jets in general and the nature of the Fanaroff–Riley morphological division of extragalactic radio sources in particular.

Sign in / Sign up

Export Citation Format

Share Document