Relation of astrophysical turbulence and magnetic reconnection
Academic Article
Overview
Research
Identity
Additional Document Info
View All
Overview
abstract
Astrophysical fluids are generically turbulent and this must be taken into
account for most transport processes. We discuss how the preexisting turbulence
modifies magnetic reconnection and how magnetic reconnection affects the MHD
turbulent cascade. We show the intrinsic interdependence and interrelation of
magnetic turbulence and magnetic reconnection, in particular, that strong
magnetic turbulence in 3D requires reconnection and 3D magnetic turbulence
entails fast reconnection. We follow the approach in Eyink, Lazarian & Vishniac
2011 to show that the expressions of fast magnetic reconnection in Lazarian &
Vishniac 1999 can be recovered if Richardson diffusion of turbulent flows is
used instead of ordinary Ohmic diffusion. This does not revive, however, the
concept of magnetic turbulent diffusion which assumes that magnetic fields can
be mixed up in a passive way down to a very small dissipation scales. On the
contrary, we are dealing the reconnection of dynamically important magnetic
field bundles which strongly resist bending and have well defined mean
direction weakly perturbed by turbulence. We argue that in the presence of
turbulence the very concept of flux-freezing requires modification. The
diffusion that arises from magnetic turbulence can be called reconnection
diffusion as it based on reconnection of magnetic field lines. The reconnection
diffusion has important implications for the continuous transport processes in
magnetized plasmas and for star formation. In addition, fast magnetic
reconnection in turbulent media induces the First order Fermi acceleration of
energetic particles, can explain solar flares and gamma ray bursts. However,
the most dramatic consequence of these developments is the fact that the
standard flux freezing concept must be radically modified in the presence of
turbulence.
