A High-Fidelity Realization of the Euclid Code Comparison $N$-body Simulation with Abacus

TL;DR

This paper demonstrates a high-accuracy, high-performance cosmological N-body simulation using the Abacus code, achieving excellent agreement with other codes and validating its precision for large-scale structure studies.

Contribution

The paper presents a high-fidelity, efficient N-body simulation with Abacus, showcasing its accuracy and performance in cosmological modeling compared to other established codes.

Findings

Abacus achieves high force accuracy and performance.

Simulation results agree well with Ramses and Pkdgrav3.

Power spectrum errors are below 0.3% at relevant scales.

Abstract

We present a high-fidelity realization of the cosmological $N$-body simulation from the Schneider et al. (2016) code comparison project. The simulation was performed with our Abacus $N$-body code, which offers high force accuracy, high performance, and minimal particle integration errors. The simulation consists of $2048^3$ particles in a $500\ h^{-1}\mathrm{Mpc}$ box, for a particle mass of $1.2\times 10^9\ h^{-1}\mathrm{M}_\odot$ with $10\ h^{-1}\mathrm{kpc}$ spline softening. Abacus executed 1052 global time steps to $z=0$ in 107 hours on one dual-Xeon, dual-GPU node, for a mean rate of 23 million particles per second per step. We find Abacus is in good agreement with Ramses and Pkdgrav3 and less so with Gadget3. We validate our choice of time step by halving the step size and find sub-percent differences in the power spectrum and 2PCF at nearly all measured scales, with $<0.3\%$ errors at $k<10\ \mathrm{Mpc}^{-1}h$. On large scales, Abacus reproduces linear theory better than $0.01\%$. Simulation snapshots are available at http://nbody.rc.fas.harvard.edu/public/S2016 .