Impulsive Solar Flares in the Parker Solar Probe Era. I. Low-energy Electron, Proton, and Alpha Beams

Multiple instruments on board the Parker Solar Probe spacecraft have detected signatures of impulsive electron and ion beam events over the course of the first 20 encounters. The energy spectra of these events are characterized by a peak originating in the low-frequency bandwidth of the FIELDS sensor and descending over time in energy until it merges with the bulk of the solar wind as observed by the Solar Wind Electrons, Alphas, and Protons suite. All events are well associated with Type III radio bursts, and some are well correlated with soft and hard X-rays generated by impulsive solar flares. These dispersive energy beam phenomena are essential in understanding particle acceleration, transport, and energy partitioning between electrons and ions as a result of impulsive solar flares. In this work, we present an analysis of said events and leverage multiwavelength observations that are conducted by instruments on multiple platforms. Our results show, for the first time, that solar flares are observed to be the source of low-energy ions in interplanetary space. This discovery has never been previously observed at such low energies by instruments at 1 au.