Tracking a beam of electrons from the low solar corona into interplanetary space with the Low Frequency Array, Parker Solar Probe and 1 au spacecraft

Type III radio bursts are the signature of outward propagating energetic electrons injected at the Sun onto interplanetary field lines, emitting electromagnetic radiation at the local plasma frequency or its harmonic. Analyzing the burst's path through space provides information about the medium they travel through as well as the intrinsic physics of the bursts themselves. Here we present our work, recently submitted for publication, in which we track an individual burst which occurred during second perihelion of Parker Solar Probe (PSP) in April 2019. First, the burst is tracked as it emerges from the low corona through tied-array imaging from 80-20 MHz using the Low Frequency Array (LOFAR). This imaging and a rudimentary 3D deprojection shows the burst is associated with open fieldlines near a non-flaring active region around E48o. Next, it is observed propagating outwards in interplanetary space with the PSP/FIELDS Radio Frequency Spectrometer (RFS), STEREO A/WAVES and Wind/WAVES instruments from 16MHz down to 100kHz. Using the differing time of arrival of the bursts radio waves to each of these spacecraft, the trajectory is retrieved (assuming it propagates near the ecliptic plane) and found to be at consistent longitudes with the LOFAR imaging. Lastly, an in situ energetic electron enhancement at STEREO A is examined. The enhancement occurs at compatible times although its onset time and duration implies the individual burst studied here only constitutes a subset of the total enhancement. This study presents a case study of a non-flare associated type III burst which survives out to 1au. It also demonstrates the power of multi-point radio studies enabled by having instrumentation distributed widely across the inner heliosphere, especially now in the era of PSP.