White Light Flare Observations from the Solar Optical Telescope onboard Hinode

In association with solar flares, we sometimes observe emission of white light continuum, which is referred to as a "gwhite light flare"h. White light flares are very infrequent, and the processes causing them are still unclear. Since close correlations of white light and hard X-ray emission were reported in many events (e.g. Hudson et al., 2006), the mechanism seems to involve emission of white light by nonthermal electron beams. The Solar Optical Telescope (SOT) is capable making observations in white light. We used SOT G-band observations to search for white-light flare counterparts to flares of GOES X-ray class C and higher. Among 155 solar flares over the first two years of the Hinode mission, we found eight white-light flare events. The white-light events tended to occur in larger events, however two occurred in C-class flares. The white light emission was located inside the flare ribbon emission, where the ribbons were observed in SOT Ca II H images. The amount of white-light emission is correlated with the emission in GOES soft X-rays and RHESSI hard X-rays. The location of the white light emission is located at almost the same place as the hard X-ray emission. However, just a weak correlation was seen between white light emission and magnetic field strength observed by the SOT Spectro Polarimeter. We consider these observations in terms of hard X-ray production and particle acceleration scenarios.