Numerical Simulations of Solar Near-relativistic Electron Transport in the Heliosphere with Different Injection Source Models, the Continuous Model and the Random Cells Model

We reproduce the time-intensity profiles of two solar near-relativistic electron events observed by ACE in interplanetary space, using numerical simulations of particle transport in the heliosphere with different injection source models. One is the commonly used continuous particle injection source model (Source-I model), and the other is the random cells particle injection source model (Source-II model). In the Source-II model, the particle injection source is composed of a number of particle injection source cells, which do not change in a time interval but undergo random movement as time transitions from one interval to the next. We find that the simulations obtained using each model can reproduce the general trends of the observations. However, the simulations obtained using the Source-I model fail to reproduce the structural details of the observations, but that using the Source-II model can replicate the fine details of the observations. Therefore, simulations with the Source-II model can fit the observational time-intensity profile much better than that with the Source-I model. We show that the spatial jumping of source cells in the Source-II model is equivalent, from the observer’s perspective, to temporal variation of the effective source intensity: cells jumping far from the magnetically connected region effectively represent source deactivation, while cells jumping back represent source reactivation. The Source-II model thus demonstrates that spatial reconfiguration of discrete source elements alone can reproduce the observed fluctuations, providing a complementary perspective to direct temporal modulation of the source.