N-body Galaxy Simulation Dataset for Chaos Analysis

Zenodo (CERN European Organization for Nuclear Research)

Abstract

This dataset contains the numerical simulation outputs presented in “The exponential growth of infinitesimal perturbations in the long-term evolution of simulated galaxies” by Asano & Portegies Zwart (arXiv:2604.12053). The simulations investigate the chaotic nature of self-gravitating N-body galaxy models by comparing reference runs and perturbed runs that differ only by an infinitesimal perturbation in the initial conditions. Each simulation consists of a pair (or ensemble) of runs: Reference run: r_xx_0 Perturbed runs: r_xx_i (i = 1, 2, ...) The perturbed runs are generated by applying a small displacement to a single particle in the initial condition of the reference run, leading to exponential divergence in phase space. List of simulations Run (i=1...3) Number of particles $N$ softening length $\epsilon$ (pc) r_00_0/r_00_i $1\times10^7$ 50.0 r_19_0/r_19_i $1.25\times10^6$ 141.4 r_20_0/r_20_i $2.5\times10^6$ 100.0 r_21_0/r_21_i $5\times10^6$ 70.7 r_xx_0 and r_xx_i (i ≥ 1) represent the reference and perturbed runs, respectively. Stellar particle data only. Data are stored in compressed NumPy binary format (.npz). Arrays have shape $T \times N \times 6$, where $T$ and $N$ are the number of snapshots and particles; the last axis corresponds to 6D phase-space coordinates $(x,y,z,v_x,v_y,v_z)$. Snapshot interval: $1\, \mathrm{kpc}/ (100 \mathrm{km\, s^{−1}}) \approx 9.78 \, \mathrm{Myr}$. Positions and velocities are given in dimensionless N-body units (Hénon 1971). Particle ordering is identical between paired runs, enabling direct comparison. Code examples https://github.com/tetsuroasano/ChaosTASPZ26

Authors 2

1. Tetsuro Asano

   Universitat de Barcelona

   Affiliation as printed

   Universitat de Barcelona

2. Simon Portegies Zwart Aachen

   Leiden University

   Affiliation as printed

   Universiteit Leiden Faculteit der Wiskunde en Natuurwetenschappen