Overview
Energetic particle populations are a pervasive feature throughout the Universe. Within our solar system, solar energetic particles (SEPs) predominantly originate from solar flares or from collisionless shocks, which are frequently driven by coronal mass ejections (CMEs). Low-energy electrons emanating from the Sun are observable remotely as solar radio bursts, resulting from accelerated electron beams interacting with plasma. This area of study still presents several open questions regarding the generation of SEPs, including their acceleration mechanisms and locations during solar flares and CMEs, as well as their escape pathways from the solar atmosphere. A primary inquiry concerns the connection between solar radio bursts and SEPs detected by spacecraft.
Research Context
The generation of solar energetic particles involves complex processes during solar flares and coronal mass ejections. Understanding how and where these particles are accelerated and how they escape the solar atmosphere remains a subject of ongoing investigation. The relationship between solar radio bursts, which indicate the presence of accelerated electron beams, and SEPs observed in situ at spacecraft is a key area of focus for connecting remote sensing observations to particle measurements. The ability to differentiate between acceleration mechanisms (flare versus shock acceleration) is critical for a comprehensive understanding of SEP events. Various properties of SEPs, including their acceleration region and origin, are still actively debated within the scientific community.
Approach
This research suggests that radio observations, particularly with facilities like the Square Kilometre Array (SKA), can offer insights into the generation and propagation of SEPs. SKA can provide high-resolution radio images and spectroscopic observations. These capabilities are proposed to determine the acceleration time, trajectory, and escape characteristics of low-energy electrons from the solar corona. The synergy between future SKA observations and current space missions is identified as a valuable approach for investigating solar activity and energetic particles across a broad spectrum of wavelengths and particle energies. By comparing SEP inferred injection times and energies from spacecraft particle data with those of electrons generating radio bursts at the Sun, a connection between radio bursts and SEPs can be established. Radio observations are also considered a method to distinguish between flare and shock acceleration. This differentiation is based on the premise that distinct types of radio bursts are indicative of different energetic processes. The potential of radio observations to serve as a tool in unraveling these processes is emphasized, given the ongoing debate surrounding the acceleration region and origin of SEPs with varied properties.
Why This Matters
Understanding the processes by which solar flares and CMEs produce energetic particles has implications for space weather. Resolving the mechanisms and locations of SEP acceleration, and how they escape the solar atmosphere, contributes to a more complete picture of solar energetic phenomena which can influence our understanding of the space environment.