Polarization intermittency in MHD and its influence on turbulent cascade

Abstract

Goldreich-Sridhar model of incompressible turbulence provides an elegant approach to describing strong MHD turbulence. It relies on the fact that interacting Alfvenic waves are independent and have random polarization. However, in case of strong interaction a spontaneous local assymetry can arise. We used direct numerical simulations to show that polarization alignment occurs and it grows larger at smaller scales. This effect would lead to a shallower spectrum and stronger anisotropy. Even small changes in these two properties will have important astrophysical consequencies, e.g. for the cosmic ray physics.