Entropy transfer from solar radio bursts to energetic particles.

Abstract

Space plasma thermodynamics is thought to be affected by wave activity. Here, we show that solar radio bursts (SRBs) can transfer entropy to solar energetic protons (SEPs), affecting their thermodynamics. In particular, our analysis (i) detects the statistically significant SEP density fluctuations, associated with SRB activity that triggers a systematic increase in the thermodynamic kappa; (ii) estimates the polytropic index of SEPs, which is anticorrelated with kappa, serving as an independent measure to validate the increase in kappa; (iii) derives the entropy transfer by using its theoretical relationship with kappa; and (iv) compares SRB wave intensity with the entropy transferring to SEPs to demonstrate their wave-particle coupling. We lastly expose the thermodynamic association between type III SRB wave intensity and SEP entropy transfer as well as their respective coupling, thus developing a paradigm for further systematic investigations among other types of wave activity and particle populations.