Classification and Modeling of Energetic Particle Events Associated with Interplanetary Shock Waves

We classify gradual energetic particle events in four types according to the variance in the flux, the characteristic duration time of the events and the maximum energy of the accelerated particles using particle and solar wind data obtained by the ACE, the SOHO and the GOES satellites. The particle flux in some events shows typical behavior of diffusive shock accelerated particles, we call these events type 1, while variance in the particle flux is complicated in other events, which suggests exiting of multiple sources of acceleration, and the maximum energy of accelerated particles is greater than 10 MeV, we call these events type 2. The other two types are; type 3: behavior of particle flux is similar as the one in type 1, but the growing time scale of the flux and total duration of enhancement of the flux are much longer, and the maximum energy of the accelerated particles is much higher than type 1, and type 4: there is no evident enhancement in a particle flux despite an interplanetary shock passage occurred. In order to clarify the difference of the particle acceleration process in these types, we perform modeling of energetic particle events by using numerical simulations, in which the stochastic differential equation method coupled with the particle splitting to diffusive acceleration is applied. In this presentation, we simulate typical events for the former two types and obtain the energy spectrum and the spatial distribution of the accelerated particles. Our results show that an injection model is one of important keys to understand difference of particle acceleration process between type 1 and type 2. The possible maximum energy of particles accelerated by CME-driven shock waves is also discussed.