Particle–particle particle–tree code for planetary system formation with individual cut-off method: GPLUM

In a standard theory of the formation planets in our Solar System, terrestrial and cores gas giants are formed through accretion kilometer-sized objects (planetesimals) protoplanetary disk. Gravitational $N$-body simulations disk system made up numerous planetesimals most direct way to study process. However, use has been limited idealized models (e.g. perfect accretion) and/or narrow spatial ranges radial direction, due number simulation runs particles available. We have developed new code equipped with particle-particle particle-tree (${\rm P^3T}$) scheme for studying planetary process: GPLUM. For each particle, GPLUM uses fourth-order Hermite calculate gravitational interactions within cut-off radii Barnes-Hut tree outside radii. existing implementations, ${\rm P^3T}$ schemes same radius all particles, making become slower when mass range planetesimal population becomes wider. solved this problem by allowing particle an appropriate depending on its mass, distance from central star, local velocity dispersion planetesimals. addition achieving significant speed-up, we also improved scalability reach good strong-scaling performance 1024 case $N=10^6$. is freely available https://github.com/YotaIshigaki/GPLUM MIT license.