Solar radio spectral fine structures and diagnostics of non-thermal processes

Baolin Tan, National Astronomical Observatories of Chinese Academy of Sciences

Solar radio observations at broadband frequency range with high temporal and spectral resolutions brought a series of new discoveries related to solar flare processes. Besides the general radio type II, III and IV bursts, spikes, dots, fibers, quasi-periodic pulsations, zebra patterns and various kinds of patches with complex structures are frequently reported. Especially in the decimeter and centimeter wavelength range for their source region very close to the flaring source region, these spectral structures are very complicated and intriguing. They are always composed with very small bursts (such as spikes, dots, and narrow band type III bursts, etc.) or bright stripes with sub-second timescales, very high brightness temperatures, and fast frequency drift rate, and sometimes strong circular polarizations. These radio spectral fine structures may present abundant useful information of the flaring source region: particles’ energy, acceleration and propagation, the background plasma density and magnetic field strength. In this talk, I will introduce the observations of solar radio spectral fine structures obtained by Chinese solar radio telescopes and other instruments in recent years, try to explain their formations, and discuss the diagnostics of solar non-thermal processes by using the above observations. These diagnostics may help us to understand well the nature of solar eruptions.