Simulation of the current sheet in a flare-active region and comparison to radio data

Numerical three-dimensional MHD simulations demonstrated that a current sheet (CS) was formed over active region AR 0365 before the flare of May 27, 2003, and the energy was accumulated in its magnetic field. Maps of the photospheric magnetic field in its preflare state were used in the simulations to define the boundary conditions instead of the usually applied approximation of the field in an active region by dipoles or magnetic charges. The CS was formed in the vicinity of a singular line as a result of focusing the magnetic field disturbances observed before the flare. The calculated CS position corresponded to the maximum brightness temperature of the flare detected by the Siberian Solar Radio Telescope SSRT (Institute of Solar-Terrestrial Physics, Russian Academy of Sciences, Siberian Branch, Irkutsk). This testifies that the flare could result from the dissipation of energy accumulated in the field of the CS, which arose over the active region.