UNIT project: Universe Nbody simulations for the Investigation of Theoretical models from galaxy surveys
Abstract
We present the UNIT Nbody cosmological simulations project, designed to provide precise predictions for nonlinear statistics of the galaxy distribution. We focus on characterizing statistics relevant to emission line and luminous red galaxies in the current and upcoming generation of galaxy surveys. We use a suite of precise particle mesh simulations (FASTPM) as well as with full Nbody calculations with a mass resolution of {∼ } 1.2× 10^9 h^{1}M_{☉} to investigate the recently suggested technique of Angulo and Pontzen to suppress the variance of cosmological simulations. We study redshiftspace distortions, cosmic voids, higher order statistics from z = 2 down to 0. We find that both two and threepoint statistics are unbiased. Over the scales of interest for baryon acoustic oscillations and redshiftspace distortions, we find that the variance is greatly reduced in the twopoint statistics and in the crosscorrelation between haloes and cosmic voids, but is not reduced significantly for the threepoint statistics. We demonstrate that the accuracy of the twopoint correlation function for a galaxy survey with effective volume of 20 (h^{1}Gpc)^{3} is improved by about a factor of 40, indicating that two pairs of simulations with a volume of 1 (h^{1}Gpc)^{3} lead to the equivalent variance of ∼150 such simulations. The Nbody simulations presented here thus provide an effective survey volume of about seven times the effective survey volume of Dark Energy Spectroscopic Instrument or Euclid. The data from this project, including dark matter fields, halo catalogues, and their clustering statistics, are publicly available.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 July 2019
 DOI:
 10.1093/mnras/stz1233
 arXiv:
 arXiv:1811.02111
 Bibcode:
 2019MNRAS.487...48C
 Keywords:

 largescale structure of the Universe;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 12 pages, 9 figures. This version matches the one accepted by MNRAS. The data from this project are publicly available at: http://www.unitsims.org