Cosmological Simulations


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Horizon Run 5 (HR5)

HR5 (Lee et al. 2021) is the first hydrodynamical cosmological simulation of the HR series devised to cover a cubic volume of 1cGpc3 with a spatial resolution of up to 1kpc. Simulation box of L=1cGpc is necessary to examine the BAO features and the enough number of clusters. The simulation starts from an initial redshift of z=200 and reaches z=0.625. Within the cubic simulation volume of (1049cMpc)3, a zoomed technique is adopted to compromise between volume and resolution with a cuboid-shaped region of 1049 ⨯ 119 ⨯ 127 cMpc3.


Figure 1: Configuration of the zoomed-in region of HR5. The left and middle panels show the zoom region projected onto the y–z and y–x planes with the size of 1049 cMpc, respectively, at the initial redshift. In the right panel, we present the evolved density at z=0.76 to show the large-scale perturbations running across the zoomed region. Different colors illustrate the different zoom levels going from blue to orange and increase resolution by a factor of two each time.


LAE-HR and CUBE-HR are spin-off simulations of HR5. This project pursues the galaxy formation history and cosmology in the distant Universe (z > 2). Especially, two simulations have complementary roles of HR5 by providing the larger box size (LAE-HR) and the periodic cubic box (CUBE-HR). The simulations provide (1) information on the baryonic gas component of mass in the universe and its past evolution and (2) simulated maps of Ly-𝛼 emitters and blobs from the cold gas component and population of young stars.

Box size (cMpc) 1049 ⨯ 119 ⨯ 127 1049 ⨯ 82 ⨯ 262 2623
Resolution (level) < 1 kpc (13-20) < 1 kpc (13-20) < 1 kpc (11-18)
Simulated time z = 200-0.625 z = 200-2.45 z = 200-2.4

Table 1: Comparison of simulation box size, resolution, and simulated time.


  • Simulation Box : 2 times larger size in y-axis of HR5
    • Large-scale power in Lbox=1 cGpc
    • Small-scale physics with < 1 kpc-resolution (=HR5)
  • Method : Zoom technique
    • large-scalep ower in the background and small-scale physics in the target region


Figure 2: Simulation box size and shape of LAE-HR. Left: a slice of the initial simulation box. The red rectangular region indicates the zoom-in region, and the orange rectangular region shows dark matter distribution. Top-right: Required simulation box size corresponding to narrowband observations assuming survey area of 10 deg at high redshifts. 10 deg corresponds to one of the largest survey area of ODIN. Bottom-right: Simulation box size and shape of the zoom-in region of LAE-HR.


  • Simulation Box : (262.114 cMpc)3
    • Similar box size with the TNG300
    • Final resolution : ∆x=1 kpc (= HR5 and LAE-HR)
    • use periodic cubic box to reduce the contamination at local boundary (without zoom technique)


Figure 3: Simulation box size and shape of CUBE-HR.

Proposal for computing time on KISTI

Proposal (٭ Written in Korean)

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