Transport and Acceleration of Solar Energetic Particles from Coronal Mass Ejection Shocks

After a brief overview of solar energetic particle (SEP) emission from coronal mass ejection (CME) shocks, we turn to a discussion of their transport and acceleration. The high energy SEP are accelerated near the Sun, and because of their well-known source location, their transport can be modeled quantitatively to obtain precise information on the injection function (number of particles emitted vs. time), including a determination of the onset time to within 1 min. For certain events, transport modeling also indicates magnetic topology with mirroring or closed field loops. Important progress has also been made on the transport of low energy SEP from very strong events, which can display exhibit interesting saturation effects and compositional variations. The acceleration of SEP by CME-driven shocks in the interplanetary medium is attributed to diffusive shock acceleration, but the spectrum of SEP production is typically modeled empirically. Recent progress has largely focused on using detailed composition measurements to determine fractionation effects of shock acceleration and even to clarify the nature of the seed population. In particular, there are many indications that the seed population is suprathermal (pre-energized) and the injection problem is not relevant to acceleration at interplanetary CME-driven shocks. We argue that the finite time available for shock acceleration provides the best explanation of the high-energy rollover.