The residual energy in freely decaying magnetohydrodynamic turbulence

Within the framework of the eddy-damped quasi-normal Markovian approximation for incompressible isotropic magnetohydrodynamic (MHD) turbulence a prediction for the inertial range scaling of the residual energy spectrum, ERk= vertical bar Ekkinetic - Emagnetick vertical bar ∼ k-7/3, is obtained. This scaling, while in contradiction to earlier theoretical results, is shown to be in agreement with high-resolution direct numerical simulations of nonhelical decaying MHD turbulence. The underlying phenomenology states a dynamic quasi-equilibrium of the small-scale turbulent dynamo and the Alfven effect