On the Remote Detection of Suprathermal Ions in the Solar Corona and their Role as Seeds for Solar Energetic Particle Production

TL;DR

This paper discusses the importance of suprathermal ions as seed particles in the solar corona for SEP events, proposing observational methods to detect these particles and improve space weather forecasting.

Contribution

It provides a comprehensive review of the evidence and theories for suprathermal seed particles and suggests a new observational approach using H I Ly-alpha line measurements.

Findings

Suprathermal particles are likely present before large SEP events.

Detection of suprathermals can be achieved through H I Ly-alpha line wing measurements.

Understanding seed particles can improve SEP event prediction.

Abstract

Forecasting large Solar Energetic Particle (SEP) events associated with shocks driven by fast coronal mass ejections (CME) pose a major difficulty in the field of Space Weather. Besides issues associated with CME initiation, the SEP intensities are difficult to predict, spanning 3 orders of magnitude at any given CME speed. Many lines of indirect evidence point to the pre-existence of suprathermal seed particles for injection into the acceleration process as a key ingredient limiting the SEP intensity of a given event. This paper outlines the observational and theoretical basis for the inference that a suprathermal particle population is present prior to large SEP events, explores various scenarios for generating seed particles and their observational signatures, and explains how such suprathermals could be detected through measuring the wings of the H I Ly-alpha line.