A high-fidelity realization of the Euclid code comparison N-body simulation with Abacus

Abstract We present a high-fidelity realization of the cosmological N-body simulation from the Schneider et al. code comparison project. The simulation was performed with our AbacusN-body code, which offers high-force accuracy, high performance, and minimal particle integration errors. The simulation consists of 20483 particles in a 500\ h^-1\, Mpc box for a particle mass of 1. 2 10⁹\ h^-1\, M_ with 10\ h^-1\, kpc spline softening. Abacus executed 1052 global time-steps to z = 0 in 107 h 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{\ per\ cent} errors at k 10\ Mpc^-1\, h. On large scales, Abacus reproduces linear theory better than 0. 01 per cent. Simulation snapshots are available at http: //nbody. rc. fas. harvard. edu/public/S2016.