Benjamin L’Huillier


Cosmologist and Astrophysicist, Research Fellow at KASI, Daejeon, South Korea

Effects of the initial conditions on cosmological N-body simulations

B. L'Huillier, C. Park & J. Kim 2014, New Astronomy 30, 79
With Changbom Park and Juhan Kim, I have studied the dependency of N-body simulations on the initial conditions (ICs). With the amount of data from large survey, cosmology has entered an era of percent level precision, and one needs to achieve a similar precision in companion cosmological N-body simulations. I have looked at the influence of the ICs, such as the starting redshift of the simulation, the preinitial configuration (glass or grid), and the order of the Lagrangian perturbation theory (LPT) used to generate the ICs, on some statistics, such as the halo mass function, the density power spectrum, and the size distribution of the large-scale structures. I have also looked at the time when this convergence is achieved for a given starting redshift.

High redshft, 2LPT initial conditions are needed if one aims to obain robust results for the mass function and power spectrum.

Effect of the LPT order on the halo mass function
Figure: Redshift evolution of the effects of the LPT order on the halo mass function. Shown is the ratio of the 1LPT to 2LPT mass function.