Formation of Anisotropic Distributions of Mildly Relativistic Electrons in Flaring Loops

V.F. Melnikov, S.P. Gorbikov, N.P. Pyatakov

Radiophysical Research Institute (NIRFI), Nizhny Novgorod, Russia

Up to date there are ample observational evidences of the existence of anisotropic distributions of mildly relativistic electrons in flaring magnetic loops. One can observe either perpendicular (Melnikov et al., ApJL 2002) or longitudinal (Altyntsev et al., ApJ 2008) anisotropy in specific flaring loops. Different types of anisotropy give different properties of the loop microwave emission (Fleishman and Melnikov, ApJ 2003) and therefore may be identified from observations. To get constraints on electron acceleration models, we simulate the pitch-angle, energy and time distributions of mildly relativistic electrons in different parts of a magnetic loop on the basis of the non-stationary Fokker-Planck equation. Solutions are obtained for the cases when an electron injection takes place in the loop top and near a footpoint. In our models we consider the cases with homogeneous and inhomogeneous background plasma, isotropic and anisotropic injections. The results of model simulations are compared with spatially resolved microwave observations.