Low-frequency Radio Observations of Picoflare Category Energy Releases in the Solar Atmosphere

We report low-frequency (80 MHz) radio observations of circularly polarized non-thermal type I radio bursts ("noise storms") in the solar corona whose estimated energy is ~10²¹ erg. These are the weakest energy release events reported to date in the solar atmosphere. The plot of the distribution of the number of bursts (dN) versus their corresponding peak flux density in the range S to S+dS shows a power-law behavior, i.e., dN vprop S ^γ dS. The power-law index γ is in the range -2.2 to -2.7 for the events reported in the present work. The present results provide independent observational evidence for the existence of picoflare category energy releases in the solar atmosphere which are yet to be explored.