Scientific Purpose

We present two large cosmological N-body simulations, called Horizon Run 2 (HR2) and Horizon Run 3 (HR3), made using $6000^3$ = 216 billions and $7210^3$ = 374 billion particles, spanning a volume of $(7.200 h^{-1} \mathrm{Gpc})^3$ and $(10.815 h^{-1} \mathrm{Gpc})^3$, respectively. These simulations improve on our previous Horizon Run 1 (HR1) up to a factor of 4.4 in volume, and range from 2600 to over 8800 times the volume of the Millennium Run. In addition, they achieve a considerably finer mass resolution, down to $1.25\times 10^{11} h^{-1} M_\odot$, allowing to resolve galaxy-size halos with mean particle separations of $1.2h^{-1} \mathrm{Mpc}$ and $1.5h^{-1} \mathrm{Mpc}$, respectively. We have measured the power spectrum, correlation function, mass function and basic halo properties with percent level accuracy, and verified that they correctly reproduce the $\Lambda$CDM theoretical expectations, in excellent agreement with linear perturbation theory. Our unprecedentedly large-volume N-body simulations can be used for a variety of studies in cosmology and astrophysics, ranging from large-scale structure topology, baryon acoustic oscillations, dark energy and the characterization of the expansion history of the Universe, till galaxy formation science - in connection with the new SDSS-III. To this end, we made a total of 35 all-sky mock surveys along the past light cone out to z=0.7 (8 from the HR2 and 27 from the HR3), to simulate the BOSS geometry. The simulations and mock surveys are already publicly available on this page (to download the preprint, click here.)


Cosmological model of the Horizon Runs (HR's)

All the HR's share the same cosmology.

Cosmological parameters of the HR's

Cosmology used for the HR's
Cosmological model $\Omega_{m,0}$ $\Omega_{b,0}$ $\Omega_{\Lambda,0}$ $n_\mathrm{s}$ $H_0$ (km/s/Mpc) $\sigma_8$
$\Lambda$CDM WMAP5 0.26 0.044 0.74 0.96 72 1/1.26

Simulations specifics

Simulations specifics
Simulations Name HR1 HR2 HR3 HR4
Box Size ($h^{-1}\mathrm{Mpc}$) 6592 7200 10815 3150
Number of CDM particles $4120^3$ $6000^3$ $7210^3$ $6300^3$
Starting redshift 23 32 27 100
Initial power spectrum generator Eisenstein & Hu (1998) CAMB Source CAMB Source CAMB Source
Initial displacement Zel'dovich Zel'dovich Zel'dovich 2LPT

Outputs from the simulation

Computers used

  1. TACHYONII: SUN Blades B6275 at KISTI
    • System resources used for the simulation(HR2/HR3)
    • 1000/1030 nodes
    • 8000/8240 CPU cores
    • 9/21 TB main memory
    • Infiniband interconnection
    • about 200/400 TB disk storage of Lustre Filesystem
    • total 20 days in wallclock time
  2. QUEST: Linux Cluster at KIAS
    • System resources used for the analysis
    • 64 nodes
    • 256 CPU cores
    • 512 GB main memory
    • Myrinet interconnection
    • about 640 TB disk storage