Media
Visualisations from my research: cosmological simulations of the large-scale structure of the Universe and the baryonification method to include baryons on top of the dark matter distribution. Light versions are shown here; the full-quality originals can be downloaded with the button under each item. Feel free to use them in talks, articles and outreach, with credit.
From the cosmic web to a galaxy cluster
4096 × 4096 px
The matter distribution in Nenya, one of the BACCO simulations: an N-body simulation of a cubic volume 512 Mpc/h on a side, evolved with 1536³ particles using the Gadget code. The large panel shows the whole box, where matter is arranged in the cosmic web of filaments, knots and voids. The three insets zoom in progressively (see the scale bars) on the most massive galaxy cluster in the simulation, until its substructures become visible.
Open the image in the deep-zoom viewer to explore all 4096 × 4096 pixels.
License: CC BY-NC 4.0 — free to reuse for non-commercial purposes, with credit: Giovanni Aricò
A dive into the most massive cluster
1920 × 1080 px · 24 fps · 25 s
A fly-through of the same Nenya simulation (512 Mpc/h box, 1536³ particles, Gadget N-body code). The camera first circles the entire simulated volume, then plunges through the cosmic web towards the most massive galaxy cluster in the box.
License: CC BY-NC 4.0 — free to reuse for non-commercial purposes, with credit: Giovanni Aricò
Baryonification, step by step
820 × 902 px · 25 s loop
Gravity-only N-body simulations accurately capture the dark matter distribution, but do not consider baryonic processes and astrophysics: gas condensing into galaxies, gas outflows from supermassive black holes accretion and supernovae explosions. Baryonification adds these effects in post-processing. For each halo, it models the density profiles of galaxies, gas and dark matter; comparing the resulting cumulative mass profile with the gravity-only one tells how far the two distributions are. Particles inside halos are then displaced in a radial way accordingly: inwards to build the central galaxy, outwards where gas is expelled, at a negligible computational cost. The animation follows these steps for a single halo. On the upper panels the density (left) and cumulative mass (right) profiles are shown, whereas in the bottom panel a halo slice is shown in logarithmic scale. The effects of baryons are exaggerated for visualisation purposes.
The algorithm is described in Aricò et al. 2020, MNRAS 495, 4800 (arXiv:1911.08471); see also its page on this site. It was later extended to gas pressure and the thermal Sunyaev–Zel’dovich effect in Aricò & Angulo 2024.
License: CC BY-NC 4.0 — free to reuse for non-commercial purposes, with credit: Giovanni Aricò
Periodic boundary conditions
1280 × 720 px · 30 fps · 35 s
A cosmological simulation follows a finite cubic volume, so what happens at its edges? The initial conditions are set on a regular lattice of particles, which are displaced with Lagrangian perturbation theory; the particles then move according to Newtonian gravity. Follow the red particle: when it passes through one side of the box, it reappears on the opposite side. This is what periodic boundary conditions mean: the box is tiled in an infinite, self-repeating grid of identical copies of itself (only the nearest ones are drawn here), so a particle leaving one box is replaced by its own image entering from the neighbouring one.
License: CC BY-NC 4.0 — free to reuse for non-commercial purposes, with credit: Giovanni Aricò