Solar Burst Analysis with 3D Loop Models

A sample of Nobeyama flares was selected and analyzed using a loop model for important flare parameters. The model for the flaring region consists of a three-dimensional dipolar magnetic field, and spatial distributions of nonthermal electrons. We constructed a database by calculating the flare microwave emission for a wide range of these parameters. Out of this database with more than 5000 cases, we extracted general flare properties by comparing the observed and calculated microwave spectra. The analysis of the Nobeyama Radio Polarimeter data was mostly based on the center-to-limb variation of the flare properties with looptop and footpoint electron distributions, and for the Nobeyama Radioheliograph maps on the resultant distribution of emission. One important aspect of this work is a comparison of the analysis of a flare using an inhomogeneous source model and a simplistic homogeneous source model. Our results clearly show that the homogeneous source hypothesis is not appropriate to describe the possible flare geometry, and its use can easily produce misleading results in terms of non-thermal electron density and magnetic field strength. A center darkening of flares was also obtained as a geometrical property of the loop-like sources.