[M-GI22] Development of computational sciences on planetary formation, evolution and surface environment

[MGI22-04] High-resolution N-body Simulations for Planet Formation: To 100 Million Particles, and Beyond

*Yasunori Hori^1,2, Shoichi Oshino³, Michiko Fujii⁴, Masaki Iwasawa⁵ (1.Astrobiology Center, National Institutes of Natural Sciences, 2.Exoplanet Detection Project, National Astronomical Observatory of Japan, 3.Center for Computational Astronomy, National Astronomy Observatory of Japan, 4.Department of Astronomy, University of Tokyo, 5.Advanced Institute for Computational Science, RIKEN)

Keywords:Planet formation, N-body simulation, GPU

In a collisional system, close encounters play an important role in dynamical evolution. Gravitational interactions between particles undergoing a close encounter are big bottlenecks in N-body simulations because of high computational costs. In fact, a direct N-body simulation in the context of planet formation faces a wall of ten thousand particles. Toward high-resolution N-body simulations with 100 million particles and beyond, we have developed three tips to overcome this sort of big wall, implementing them into our N-body code for planet formation: (i) a tree-based hybrid N-body scheme which reduces numerical integrations of gravitational interactions among particles, PPPT method (Oshino et al. 2011), (ii) GPU clusters which allow us to handle a large number of particles, (iii) parallelization and optimization for accelerating numerical integrations, specifically, a multi-purpose platform for a parallelized particle-particle simulation, the so-called “Framework for Developing Particle Simulator” (FDPS: Iwasawa et al. 2015). In this talk, we introduce what our brand-new N-body code is like and its performance and capability. We also show our preliminary results of N-body simulations of terrestrial planet formation, using ~ 0.1-1 million planetesimals.