Perturbation-theory informed integrators for cosmological simulations
- Autor(en)
- Florian List, Oliver Hahn
- Abstrakt
Large-scale cosmological simulations are an indispensable tool for modern cosmology. To enable model-space exploration, fast and accurate predictions are critical. In this paper, we show that the performance of such simulations can be further improved with time-stepping schemes that use input from cosmological perturbation theory. Specifically, we introduce a class of time-stepping schemes derived by matching the particle trajectories in a single leapfrog/Verlet drift-kick-drift step to those predicted by Lagrangian perturbation theory (LPT). As a corollary, these schemes exactly yield the analytic Zel'dovich solution in 1D in the pre-shell-crossing regime (i.e. before particle trajectories cross). One representative of this class is the popular FastPM scheme by Feng et al. 2016, which we take as our baseline. We then construct more powerful LPT-inspired integrators and show that they outperform FastPM and standard integrators in fast simulations in two and three dimensions with $\mathcal{O}(1 - 100)$ timesteps, requiring less steps to accurately reproduce the power spectrum and bispectrum of the density field. Furthermore, we demonstrate analytically and numerically that, for any integrator, higher-order convergence cannot be achieved in the post-shell-crossing regime, owing to the lacking regularity of the acceleration field. Also, we study the impact of the timestep spacing and of a decaying mode present in the initial conditions. Importantly, we find that symplecticity of the integrator plays a minor role for fast approximate simulations with a small number of timesteps.
- Organisation(en)
- Institut für Astrophysik, Institut für Mathematik
- Journal
- Journal of Computational Physics
- Band
- 513
- Anzahl der Seiten
- 44
- ISSN
- 0021-9991
- Publikationsdatum
- 09-2024
- Peer-reviewed
- Ja
- ÖFOS 2012
- 103004 Astrophysik, 103043 Computational Physics
- Schlagwörter
- ASJC Scopus Sachgebiete
- Computational Mathematics, Physics and Astronomy(all), Applied Mathematics, Numerical Analysis, Computer Science Applications, Modelling and Simulation, Physics and Astronomy (miscellaneous)
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/perturbationtheory-informed-integrators-for-cosmological-simulations(1c3e8c87-5518-459f-ac95-5f0e3a68e1f4).html