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Main Authors: Hirashima, Keiya, Fujii, Michiko S., Saitoh, Takayuki R., Harada, Naoto, Nomura, Kentaro, Yoshikawa, Kohji, Hirai, Yutaka, Asano, Tetsuro, Moriwaki, Kana, Iwasawa, Masaki, Okamoto, Takashi, Makino, Junichiro
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2510.23330
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author Hirashima, Keiya
Fujii, Michiko S.
Saitoh, Takayuki R.
Harada, Naoto
Nomura, Kentaro
Yoshikawa, Kohji
Hirai, Yutaka
Asano, Tetsuro
Moriwaki, Kana
Iwasawa, Masaki
Okamoto, Takashi
Makino, Junichiro
author_facet Hirashima, Keiya
Fujii, Michiko S.
Saitoh, Takayuki R.
Harada, Naoto
Nomura, Kentaro
Yoshikawa, Kohji
Hirai, Yutaka
Asano, Tetsuro
Moriwaki, Kana
Iwasawa, Masaki
Okamoto, Takashi
Makino, Junichiro
contents A major goal of computational astrophysics is to simulate the Milky Way Galaxy with sufficient resolution down to individual stars. However, the scaling fails due to some small-scale, short-timescale phenomena, such as supernova explosions. We have developed a novel integration scheme of $N$-body/hydrodynamics simulations working with machine learning. This approach bypasses the short timesteps caused by supernova explosions using a surrogate model, thereby improving scalability. With this method, we reached 300 billion particles using 148,900 nodes, equivalent to 7,147,200 CPU cores, breaking through the billion-particle barrier currently faced by state-of-the-art simulations. This resolution allows us to perform the first star-by-star galaxy simulation, which resolves individual stars in the Milky Way Galaxy. The performance scales over $10^4$ CPU cores, an upper limit in the current state-of-the-art simulations using both A64FX and X86-64 processors and NVIDIA CUDA GPUs.
format Preprint
id arxiv_https___arxiv_org_abs_2510_23330
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The First Star-by-star $N$-body/Hydrodynamics Simulation of Our Galaxy Coupling with a Surrogate Model
Hirashima, Keiya
Fujii, Michiko S.
Saitoh, Takayuki R.
Harada, Naoto
Nomura, Kentaro
Yoshikawa, Kohji
Hirai, Yutaka
Asano, Tetsuro
Moriwaki, Kana
Iwasawa, Masaki
Okamoto, Takashi
Makino, Junichiro
Astrophysics of Galaxies
Distributed, Parallel, and Cluster Computing
Machine Learning
Computational Physics
A major goal of computational astrophysics is to simulate the Milky Way Galaxy with sufficient resolution down to individual stars. However, the scaling fails due to some small-scale, short-timescale phenomena, such as supernova explosions. We have developed a novel integration scheme of $N$-body/hydrodynamics simulations working with machine learning. This approach bypasses the short timesteps caused by supernova explosions using a surrogate model, thereby improving scalability. With this method, we reached 300 billion particles using 148,900 nodes, equivalent to 7,147,200 CPU cores, breaking through the billion-particle barrier currently faced by state-of-the-art simulations. This resolution allows us to perform the first star-by-star galaxy simulation, which resolves individual stars in the Milky Way Galaxy. The performance scales over $10^4$ CPU cores, an upper limit in the current state-of-the-art simulations using both A64FX and X86-64 processors and NVIDIA CUDA GPUs.
title The First Star-by-star $N$-body/Hydrodynamics Simulation of Our Galaxy Coupling with a Surrogate Model
topic Astrophysics of Galaxies
Distributed, Parallel, and Cluster Computing
Machine Learning
Computational Physics
url https://arxiv.org/abs/2510.23330