[M-GI30] Computational sciences on the universe, galaxies, stars, planets, and their environments

[MGI30-P02] PIC simulation of injection of pickup ions at an oblique heliospheric termination shock

*Shuichi Matsukiyo¹, Yosuke Matsumoto² (1.Faculty of Engineering Sciences, Kyushu University, 2.Institute for Advanced Academic Research, Chiba University)

Keywords:PIC simulation, particle acceleration, collisionless shock

The heliospheric termination shock (HTS) is thought to be an ideal laboratory to study the injection process, initial phase of particle acceleration process in a collisionless shock, because the anomalous cosmic rays are believed to be accelerated there. The Voyager spacecraft observed the so-called termination shock particles which are accelerated pickup ions (PUIs), although their flux was much less than expected. On the other hand, Goiacalone et al. (2021) recently showed that the acceleration rate of low energy (~50 keV) PUIs is more or less independent of the position in the HTS. This implies that a universal mechanism of acceleration of low energy PUIs at the HTS may work. In their simulation upstream turbulence in the solar wind is taken into account and nonthermal PUIs ooze from the shock into upstream along the magnetic field penetrating locally oblique to the shock surface. Therefore, local obliquity of the shock angle may be important in initial acceleration of PUIs. Here, the shock angle is defined as the angle between shock normal and upstream magnetic field. In this study we focus the injection of PUIs at an oblique HTS. The microstructure of a local oblique HTS mediated by the presence of PUIs is discussed by performing two-dimensional full particle-in-cell simulation using the supercomputer Fugaku especially focusing on the process of initial acceleration of PUIs.