Signatures of Type III Radio Bursts from Small-scale Reconnection Events in the Solar Wind

We look for evidence of energetic particles in the solar wind, that could be produced by reconnection in the solar wind itself or reconnection in the lower corona, where particles escape on open field lines, from e.g. interchange reconnection.We expect reconnection to be common at the current sheets that separate the thin magnetic strands that make up the corona and solar wind, but whether it is efficient at accelerating particles is an open question. Type III radio bursts have been very frequently observed in the solar wind over the past few decades. Energetic electron beams propagating along magnetic field lines cause a bump-on-tail instability generating Langmuir waves. Produced by their interaction with other particles and waves, type III bursts exhibit a characteristic drift in frequency as they propagate through the density gradient in the field. An interesting question is whether there is a ubiquitous presence of type IIIs in the radio ‘background’ observed. The radio background outside of clearly identified bursts may actually be comprised of multiple overlapping events. The time-lag technique that was developed to study subtle delays in light curves from different EUV channels [Viall & Klimchuk 2012] can also be used to detect subtle delays at different frequencies in the radio background even when there is no hint in the individual light curves. The FIELDS instrument onboard the Parker Solar Probe (PSP) is utilized to investigate the solar wind for these signatures. We perform a systematic study of the observed type III storms in Encounters 1-5, to understand the signatures that can identify their presence and the different features observed using the technique. Our findings are then employed to study the times where no activity is visibly detected by the instrument. We are currently analyzing multiple periods of no visible activity and will report our findings.