Simulating the effect of SEP transport on the electron energy spectrum

Abstract:

SEP electron spectra, observed at 1AU, are shaped by a combination of acceleration and transport processes, and disentangling the role and effects of each process remains difficult. In this work we simulate the transport of SEP electrons with a power law distribution from the Sun to 1AU and show that transport effects can significantly alter the spectral shape. For the omni-directional intensity, a roll-over (or break) in the spectra are observed above ~100keV, leading to a softer spectrum at higher energies. In addition, the spectrum of sunward propagating particles appears harder than that of anti-sunward propagating particles; an artifact from energy dependent pitch-angle scattering. We show that these spectral changes are both energy (being more efficient at intermediate/high energies) and spatially (becoming very inefficient closer to the Sun) dependent. The results suggest that observed spectra between ~10 - 100keV may reflect the original acceleration spectrum. We also compare the results with STEREO observations.