The turbulent chiral-magnetic cascade in the early universe

Tuesday, 11 July, 2017

Published in: 

Astrophys. J. Lett. 845, L21 (2017)

The presence of asymmetry between fermions of opposite handedness in plasmas of relativistic particles can lead to exponential growth of a helical magnetic field via a small-scale chiral dynamo instability known as the chiral magnetic effect. Here, we show, using dimensional arguments and numerical simulations, that this process produces through the Lorentz force chiral magnetically driven turbulence. A k^{-2} magnetic energy spectrum emerges via inverse transfer over a certain range of wavenumbers k. The total chirality (magnetic helicity plus normalized chiral chemical potential) is conserved in this system. Therefore, as the helical magnetic field grows, most of the total chirality gets transferred into magnetic helicity until the chiral magnetic effect terminates. Quantitative results for height, slope, and extent of the spectrum are obtained. Consequences of this effect for cosmic magnetic fields are discussed.

Author(s): 

Axel Brandenburg
Jennifer Schober
Igor Rogachevskii
Tina Kahniashvili
Alexey Boyarsky
Jurg Frohlich
Oleg Ruchayskiy
Nathan Kleeorin