Non-locality of the Turbulent Electromotive Force

The generation of large-scale magnetic fields ((B) over bar) in astrophysical systems is driven by the mean turbulent electromotive force ((E) over bar), the cross-correlation between local fluctuations of velocity and magnetic fields. This can depend non-locally on (B) over bar through a convolution kernel K-ij. In a new approach to find K-ij, we directly fit the time-series data of (E) over bar versus (B) over bar from a galactic dynamo simulation using singular value decomposition. We calculate the usual turbulent transport coefficients as moments of K-ij, and show the importance of including non-locality over eddy length-scales to fully capture their amplitudes and that higher order corrections to the standard transport coefficients are small in this case.