Comment on "N-body simulations of gravitational dynamics" by Dehnen and Read

TL;DR

This paper critiques a review of N-body simulations, emphasizing missing milestones, the importance of particle number and force smoothing, and the need to consider constraints for accurate gravitational modeling.

Contribution

It highlights overlooked historical milestones, stresses the significance of particle number and force smoothing, and discusses constraints affecting N-body simulation accuracy.

Findings

Historical milestones in N-body simulations are incomplete.

Particle number and force smoothing are crucial for realistic simulations.

Published constraints limit the scope of feasible N-body simulations.

Abstract

It is shown that the historical summary of the growth in size of N-body simulations as measured by particle number in this review is missing some key milestones. Size matters, because particle number with appropriate force smoothing is a key method to suppress unwanted discreteness, so that the initial conditions and equations of motion are appropriate to growth by gravitational instability in a Poisson-Vlasov system appropriate to a Universe with dark matter. Published strong constraints on what can be done are not included in the review.