Cosmological simulations allow us to study the emergence of structure in Universe: Starting from our understanding of the very early universe, we perform simulations of a wide range of scales: how dark matter collapses and forms the seeds of galaxies, how the large-scale filamentary network of galaxies arises from the counteracting forces of the expansion of the universe and the pull of gravity; how the largest collapsed objects in the universe - clusters of hundreds and thousands of galaxies - form and evolve and what we can learn about our universe from those most extreme objects; and how galaxies form as part of the large-scale structure that feeds them with gas. Finally, we study also how active galactic nuclei regulate the thermodynamic properties of gas in galaxy clusters and the impact they have on the formation of stars in massive galaxies.

Aside from astrophysical questions, we are also interested in developing numerical simulation techniques that allow us to answer questions about the universe both more precisely and more efficiently.

This movie shows the evolution of the gas during the formation of a very massive galaxy cluster from the RHAPSODY-G simulations. The gas density is shown in gray colors with the gas temperature overlaid in orange. The abundance and properties of these massive systems contain a wealth of information about the physics and cosmology of our Universe. The image is 17 Mpc/h wide, projection depth is 5 Mpc/h.
Visualization by Oliver Hahn
Simulation: Oliver Hahn, Davide Martizzi

This movie shows the formation of the cosmic web of dark matter from random fluctuations in the early universe. The intricate network of filaments hosts dark matter halos, the most massive of them are rendered in bright yellow hinting at the galaxies they are thought to host in the LCDM cosmological model.
Visualization by Ralf Kaehler, Carter Emmart, Tom Abel for AMNH planetarium show "The Dark Universe"
Simulation: Tom Abel, Oliver Hahn