The growth of chiral magnetic instability in a large-scale magnetic field

Yasufumi Kojima,Yuri Miura

doi:10.1093/ptep/ptz027

Yasufumi Kojima, Yuri Miura

Open Access

https://doi.org/10.1093/ptep/ptz027

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Abstract

The chiral magnetic effect emerges from a miroscopic level, and its interesting consequences have been discussed in relation to the dynamics of the early universe, neutron stars, and quark–gluon plasma. An instability is caused by an anomalous electric current along the magnetic field. We investigate the effects of plasma motion on the instability in terms of linearized perturbation theory. A magnetic field can inhibit magnetohydrodynamic waves to a remarkable degree, and thereby affects the instability mode. We also found that the unstable mode consists of coupling between Alfven and one of the magneto-acoustic waves. Therefore, the propagation of a mixed Alfven wave driven by magnetic tension is very important. The direction of the unperturbed magnetic field favors the wave propagation of the instability mode, when Alfven speed exceeds sound speed.

Highlights

It is widely recognized that the magnetohydrodymamics (MHD) is capable of describing a variety of astrophysical phenomena
The chiral magnetic instability is inherent in an electromagnetic field with the electric current parallel to the magnetic field
All modes are described by solving the resultant dispersion relation, no matter whether they are stable or unstable

Summary

Introduction

It is widely recognized that the magnetohydrodymamics (MHD) is capable of describing a variety of astrophysical phenomena. The electric current (1) is discussed in a context of mean-field MHD dynamo(e.g.,[21,22,23]). Computational cost may be high in the high resolution simulations Another example of the form (1) is force-free magnetic fields (e.g., [21, 26]), in which Lorentz force vanishes j × B = 0. The background state is assumed to be homogeneous with uniform magnetic field, and small perturbations propagate as MHD waves in the absence of chiral magnetic effect. This problem was partially studied[24], where the modification is found, but the general property is not clear.

Equations

Chiral magnetic instability

Effect of thermal pressure

Effect of a uniform magnetic field

Magnetohydrodyamical effects

Summary and Discussion