Energetics of turbulence generated by chiral MHD dynamos
  An asymmetry in the number density of left- and right-handed fermions is
known to give rise to a new term in the induction equation that can result in a
dynamo instability. At high temperatures, when a chiral asymmetry can survive
for long enough, this chiral dynamo instability can amplify magnetic fields
efficiently, which in turn drive turbulence via the Lorentz force. While it has
been demonstrated in numerical simulations that this chiral magnetically driven
turbulence exists and strongly affects the dynamics of the magnetic field, the
details of this process remain unclear. The goal of this paper is to analyse
the energetics of chiral magnetically driven turbulence and its effect on the
generation and dynamics of the magnetic field using direct numerical
simulations. We study these effects for different initial conditions, including
a variation of the initial chiral chemical potential and the magnetic Prandtl
number, Pm. In particular, we determine the ratio of kinetic to magnetic
energy, Upsilon, in chiral magnetically driven turbulence. Within the parameter
space explored in this study, Upsilon reaches a value of approximately
0.064-0.074 -independently of the initial chiral asymmetry and for Pm=1. Our
simulations suggest, that Upsilon decreases as a power law when increasing Pm
by decreasing the viscosity. While the exact scaling depends on the details of
the fitting criteria and the Reynolds number regime, an approximate result of
Upsilon(Pm)=0.1 Pm^{-0.4} is reported. Using the findings from our numerical
simulations, we analyse the energetics of chiral magnetically driven turbulence
in the early Universe.
