2003/05/21 by Naoki Yoshida, Naoshi Sugiyama, Lars Hernquist · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Galaxies: Formation, Evolution, Phenomena #Scientific Research and Discoveries #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.2003.06829.x
published as Mon.Not.Roy.Astron.Soc. 344 (2003) 481-491 · Version accepted by MNRAS. Minor typos corrected
arxiv created 2003/05/21 · openalex publication_date 2003/09/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We critically examine how the evolution of the matter density field in cosmological simulations is affected by details of setting up initial conditions. We show that it is non-trivial to realize an initial distribution of matter in N-body/hydrodynamic simulations so that the baryon and dark matter density fluctuations and their velocities evolve consistently as theoretically predicted. We perform a set of cosmological simulations and use them to distinguish and verify an appropriate method for generating initial conditions. We show that a straightforward way of applying the Zel'dovich approximation to each component using distinct transfer functions results in an incorrect growth of density fluctuations and that it is necessary to correct velocities at the initial epoch. The unperturbed uniform particle distribution must be also generated appropriately to avoid tight coupling of the baryonic and dark matter components. We recommend using independent ‘glass’ particle distributions, using distinct transfer functions for baryons and dark matter, and taking into account the difference in the velocity fields at the initialization epoch. The proposed method will be useful for studies of the evolution of the intergalactic medium and the formation of the first cosmological objects using numerical simulations.