Millimeter Interferometer Observations of Flares

This paper addresses the current state of millimeter interferometry of solar ares and the issues which can be addressed by such observations. Millimeter interferometers such as BIMA detect gyrosynchrotron emission from MeV{energy electrons in the impulsive phase of solar ares as well as from hot dense plasma in the thermal decay phase. BIMA now consists of 10 antennas and is capable of snapshot imaging of solar ares with excellent spatial resolution and dynamic range of up to 100. The properties of MeV{energy electrons deduced from such observations vary widely: in some ares they are present for a much shorter time than the lower{energy hard{X{ray producing electrons, while in other ares they are present longer. Examples of both circumstances are given. It is widely observed that the energy distribution determined from the optically{thin radio spectrum is inconsistent with that determined from hard X{ray data: generally this is interpreted to mean that the electron energy distribution is atter at higher energies, but even this interpretation can run into diiculties. This discrepancy between radio and hard X{ray spectral indices may be revealing something fundamental about electron acceleration in solar ares.