Scientific Purpose

Horizon Run 5 (HR5) is a cosmological hydrodynamical simulation which captures the properties of the Universe on a $\mathrm{Gpc}$ scale while achieving a resolution of 1 kpc. This enormous dynamic range allows us to simultaneously capture the physics of the cosmic web on very large scales and account for the formation and evolution of dwarf galaxies on much smaller scales. Inside the simulation box, we zoom-in on a high-resolution cuboid region with a volume of 1049$\times$114$\times$114 $\mathrm{cMpc}^3$. The sub-grid physics chosen to model galaxy formation includes radiative heating/cooling, reionization, star formation, supernova feedback, chemical evolution tracking the enrichment of oxygen and iron, the growth of supermassive black holes and feedback from active galactic nuclei (AGN) in the form of a dual jet-heating mode. For this simulation, we implemented a hybrid MPI-OpenMP version of the RAMSES code, specifically targeted for modern many-core many thread parallel architectures. Light cone space data was generated on-the-fly, as well as snapshots. For the post-processing, we extended the Friends-of-Friend (FoF) algorithm and developed a new galaxy finder PGalF to analyze the large outputs of HR5. The simulation successfully reproduces observations, such as the cosmic star formation history and connectivity of galaxy distribution. HR5 contains cosmological structures in a wide range of scales, from filaments of a few $\mathrm{cMpc}$ lengths to voids of $\sim\,$100 $\mathrm{cMpc}$ radii. The simulation also indicates that hydrodynamical effects on small scales impact galaxy clustering up to very large scales near and beyond the baryonic acoustic oscillation (BAO) scale. Hence, caution should be taken when using that scale as a cosmic standard ruler: one needs to understand the corresponding biases carefully. The simulation is expected to be an invaluable asset for the interpretation of upcoming deep surveys of the Universe.


Cosmological model of the Horizon Run 5

All the HR's share the same cosmology, but the HR5 reflects recent updates of the Planck observation.

Cosmological parameters of the HR's

Cosmology used for the HR5's
Cosmological model $\Omega_{m,0}$ $\Omega_{b,0}$ $\Omega_{\Lambda,0}$ $n_\mathrm{s}$ $H_0$ (km/s/Mpc) $\sigma_8$
$\Lambda$CDM Planck 0.3 0.047 0.7 - 68.4 1/1.225

Simulations specifics
Simulations Name HR1 HR2 HR3 HR4 HR5
Box Size ($c\mathrm{Mpc}$) 9417 10285 15450 4436 1049
Number of CDM particles 4120$^3$ 6000$^3$ 7210$^3$ 6300$^3$ gas cells + particles
Starting redshift 23 32 27 100 200
Initial power spectrum generator Eisenstein & Hu (1998) CAMB Source CAMB Source CAMB Source CAMB Source
Initial displacement Zel'dovich Zel'dovich Zel'dovich 2LPT 2LPT
Code GOTPM (Dubinski, Kim, Park 2004) GOTPM GOTPM GOTPM RAMSES (Teyssier 2002)

Outputs from the simulation