The largest and most accurate digital representation of our cosmic neighborhood has now been published by researchers within the project “Simulations Beyond the Local Universe"
(SIBELIUS). The “Local Universe” refers to a volume extending approximately 600 Million lightyears from our Milky Way, and includes familiar structures like the Virgo, Coma and Perseus galaxy clusters, the Local Void, and at the center, the Milky Way and Andromeda galaxies.

Evolution of the “Local Universe”
The simulation recreates the entire evolution of the “Local Universe”, from the Big Bang to the present. It produced over one Petabyte of data by simulating the gravitational interaction of more than 130 billion simulation particles for several weeks on the DiRAC COSmology MAchine (COSMA) operated by the Institute for Computational Cosmology of Durham University.

Local environment
At the center of the SIBELIUS simulation, we find the Milky Way galaxy and our nearest massive neighbor, the Andromeda galaxy (M31). The left panel shows the dark matter distribution in a 50x50x50 Mpc region centered on the Milky Way, colored by projected density and the velocity dispersion of simulated particles. Our two most massive neighbors, the Virgo cluster and the Fornax/Eridanus groups are highlighted. The middle and right panels zoom into a 15x15x15 Mpc and 5x5x5 Mpc region, respectively. The right panel highlights the Milky Way and Andromeda (M31). The SIBELIUS simulation provides a highly detailed reproduction of our cosmic environment, permitting detailed studies of its gravitational formation. Credit: Stuart McAlpine.

Primordial fluctuations are the ancestors of all presently observed structures
Creating digital re-simulations of the Universe is an essential tool to understand the fundamental physical processes determining the origin and evolution of all cosmic structures, including the observed galaxies. According to the current paradigm of cosmology, all cosmic structures form by gravitational instability from tiny primordial density fluctuations generated during the Big Bang. These primordial fluctuations are the ancestors of all presently observed structures and retain a memory of the physical processes determining their origin and evolution. A significant challenge in creating faithful computer representations of our Universe is to find the hitherto unknown initial matter fluctuations that gave rise to the observed galaxy distribution.

The simulation contains counterparts of our own Milky Way
The team used novel statistical data analysis methods, pioneered by the Stockholm group, to
construct the exact initial conditions for the gravitational formation of the Nearby Universe. The new simulation, SIBELIUS-DARK, is part of the "Simulations Beyond the Local Universe" (SIBELIUS) project led by research groups from the UK, Sweden, Finland, France, and the Netherlands. In contrast to standard simulations, SIBELIUS-DARK, is conditioned to reproduce our specific patch of the Universe and resembles the present-day structures in the vicinity of our galaxy. Precisely, the Virgo, Coma, and Perseus clusters of galaxies, the 'Great Wall' and the 'Local Void' – our cosmic habitat – are faithfully reproduced. The center of the simulation contains the virtual counterparts of our own Milky Way and our nearby massive neighbor, the Andromeda galaxy

Jens Jasche
Jens Jasche, Department of Physics at the Stockholm University

Unique opportunity to study the formation of galaxies
“The simulation now allows us to access the dynamic formation history of the local group and provides a unique opportunity to study the formation of galaxies in our Local Universe, providing further stringent tests of the standard model of cosmology”, says Jens Jasche at Stockholm University and one of the researchers behind the simulation.

The team published their results in the journal Monthly Notices of the Royal Astronomical Society on February, 2022.
Read article: “SIBELIUS-DARK: a galaxy catalogue of the Local Volume from a constrained realisation simulation”