4:00 PM - 4:15 PM
[PEM16-03] Large-scale test particle simulation on the invasion and transport process of galactic cosmic rays into the heliosphere
Keywords:Cosmic ray, Heliosphere
Most of the galactic cosmic rays (GCRs) coming from interstellar space are prevented from entering the heliosphere. Only a fraction of them can propagate deep inside the heliosphere and be observed on the Earth. Their motion in the heliosphere is strongly affected by the solar modulation effects.
In our research, we conduct test particle simulation using the electromagnetic field data of the steady heliosphere reproduced by global MHD simulation to investigate the invasion and transport process of GCRs into the heliosphere. We analyze particle orbits and statistics of GCRs with energies of 10 GeV to 1 TeV that reached the inner boundary at 50 AU. In the last meeting, for ~10 GeV and ~1 TeV GCRs arriving at the inner boundary, we showed the relation between the initial particle position outside the heliosphere and the arrival position of particles on the inner boundary, and reported that many GCRs with ~10GeV invade the heliosphere from the current sheet formed on the solar equatorial plane and are more likely to reach high latitude regions on the inner boundary, while GCRs with ~1TeV invade the heliosphere from the heliotail and are more likely to reach low latitude regions on the inner boundary. However, the number of test particles was at most 3 million, which was insufficient in accuracy for particle statistics. Therefore, in this research, we conduct large-scale test particle simulation with a particle number of 10 billion to discuss particle statistics with high accuracy. Based on the calculation results, we will clarify the sensitivity of each energy band of GCRs to the heliospheric structure and how that structure contributes to their statistics.
In our research, we conduct test particle simulation using the electromagnetic field data of the steady heliosphere reproduced by global MHD simulation to investigate the invasion and transport process of GCRs into the heliosphere. We analyze particle orbits and statistics of GCRs with energies of 10 GeV to 1 TeV that reached the inner boundary at 50 AU. In the last meeting, for ~10 GeV and ~1 TeV GCRs arriving at the inner boundary, we showed the relation between the initial particle position outside the heliosphere and the arrival position of particles on the inner boundary, and reported that many GCRs with ~10GeV invade the heliosphere from the current sheet formed on the solar equatorial plane and are more likely to reach high latitude regions on the inner boundary, while GCRs with ~1TeV invade the heliosphere from the heliotail and are more likely to reach low latitude regions on the inner boundary. However, the number of test particles was at most 3 million, which was insufficient in accuracy for particle statistics. Therefore, in this research, we conduct large-scale test particle simulation with a particle number of 10 billion to discuss particle statistics with high accuracy. Based on the calculation results, we will clarify the sensitivity of each energy band of GCRs to the heliospheric structure and how that structure contributes to their statistics.