scholarly journals Radio polarization maps of shell-type supernova remnants – I. Effects of a random magnetic field component and thin-shell models

2016 ◽  
Vol 459 (1) ◽  
pp. 178-198 ◽  
Author(s):  
R. Bandiera ◽  
O. Petruk
Keyword(s):  
Magnetic Field ◽  
Thin Shell ◽  
Supernova Remnants ◽  
Field Component ◽  
Magnetic Field Component ◽  
Shell Type ◽  
Shell Models ◽  
Random Magnetic Field

scholarly journals Magnetic fields in massive spirals: The role of feedback and initial conditions

2018 ◽  
Vol 619 ◽  
pp. L5 ◽  
Author(s):  
Evangelia Ntormousi
Keyword(s):  
Magnetic Field ◽  
Velocity Field ◽  
Magnetic Fields ◽  
Field Component ◽  
Initial Conditions ◽  
Magnetic Field Component ◽  
Stellar Feedback ◽  
Random Magnetic Field ◽  
Supernova Feedback ◽  
The Magnetic Field

Context. Magnetic fields play a very important role in the evolution of galaxies through their direct impact on star formation and stellar feedback-induced turbulence. However, their co-evolution with these processes has still not been thoroughly investigated, and the possible effect of the initial conditions is largely unknown. Aims. This Letter presents the first results from a series of high-resolution numerical models, aimed at deciphering the effect of the initial conditions and of stellar feedback on the evolution of the galactic magnetic field in isolated Milky Way-like galaxies. Methods. The models start with an ordered magnetic field of varying strength, either poloidal or toroidal, and are evolved with and without supernova feedback. They include a dark matter halo, a stellar and a gaseous disk, as well as the appropriate cooling and heating processes for the interstellar medium. Results. Independently of the initial conditions, the galaxies develop a turbulent velocity field and a random magnetic field component in under 15 Myr. Supernova feedback is extremely efficient in building a random magnetic field component up to large galactic heights. However, a random magnetic field emerges even in runs without feedback, which points to an inherent instability of the ordered component. Conclusions. Supernova feedback greatly affects the velocity field of the galaxy up to large galactic heights, and helps restructure the magnetic field up to 10 kpc above the disk, independently of the initial magnetic field morphology. On the other hand, the initial morphology of the magnetic field can accelerate the development of a random component at large heights. These effects have important implications for the study of the magnetic field evolution in galaxy simulations.

Effects of the axial magnetic field component on the electron trajectory in the wiggler section

1998 ◽  
Vol 34 (5) ◽  
pp. 3467-3470
Author(s):  
A.C.C. Migliano ◽  
A.C.J. Paes ◽  
Y.C. De Polli ◽  
C.R.S. Stopa ◽  
J.R. Cardoso
Keyword(s):  
Magnetic Field ◽  
Field Component ◽  
Axial Magnetic Field ◽  
Magnetic Field Component ◽  
Electron Trajectory

scholarly journals MHD aspect of current sheet oscillations related to magnetic field gradients

2009 ◽  
Vol 27 (1) ◽  
pp. 417-425 ◽  
Author(s):  
N. V. Erkaev ◽  
V. S. Semenov ◽  
I. V. Kubyshkin ◽  
M. V. Kubyshkina ◽  
H. K. Biernat
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Field Component ◽  
Short Wave ◽  
Magnetic Field Component ◽  
Wave Number ◽  
Dispersion Function ◽  
Small Scale ◽  
Magnetic Field Gradients ◽  
Normal Magnetic Field

Abstract. One-fluid ideal MHD model is applied for description of current sheet flapping disturbances appearing due to a gradient of the normal magnetic field component. The wave modes are studied which are associated to the flapping waves observed in the Earth's magnetotail current sheet. In a linear approximation, solutions are obtained for model profiles of the electric current and plasma densities across the current sheet, which are described by hyperbolic functions. The flapping eigenfrequency is found as a function of wave number. For the Earth's magnetotail conditions, the estimated wave group speed is of the order of a few tens kilometers per second. The current sheet can be stable or unstable in dependence on the direction of the gradient of the normal magnetic field component. The obtained dispersion function is used for calculation of the flapping wave disturbances, which are produced by the given initial Gaussian perturbation at the center of the current sheet and propagating towards the flanks. The propagating flapping pulse has a smooth leading front, and a small scale oscillating trailing front, because the short wave oscillations propagate much slower than the long wave ones.

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