Stuart McAlpine, John Helly, Matthieu Schaller, Till Sawala, Guilhem Lavaux, Jens Jasche, Carlos Frenk, Adrian Jenkins, John Lucey and Peter Johansson
Monthly Notices of the Royal Astronomical Society, 2022, tmp.348M
Over the past thirty years cosmologists have developed a standard model of cosmology — Lambda Cold Dark Matter (LCDM) which explains a plethora of astronomical data, from the properties of the microwave background radiation (the heat left over from the Big Bang) to the number and spatial distribution of galaxies in the Universe. Computer simulations lie at the heart of this development: they allow predictions to be made of the distribution of dark matter and galaxies, especially in the non-linear regime, the best observed.
Cosmological simulations usually follow a “typical” patch of a LCDM Universe. But the simulations of the Sibelius project are different: using advanced statistical techniques, they are conditioned to reproduce, by the present day, the structures that we see in the local universe, specifically in the 2MASS+ galaxy survey.
The volume simulated in Sibelius is a sphere around us of radius 200 Mpc. Galaxies in this dark matter-only simulation are followed with the semi-analytic galaxy formation model GALFORM. Structures familiar to astronomers, such as the Virgo, Coma and Perseus clusters of galaxies, the “Great Wall” and the “Local Void” — our cosmic habitat – emerge from LCDM initial conditions and are faithfully reproduced in the simulation. At the centre there is a pair of galaxies, the virtual counterparts of our own Milky Way and our massive neighbour, the Andromeda galaxy. Sibelius enables novel tests of LCDM and of galaxy formation theory. In addition it offers the possibility of studying in detail the formation paths and physical properties of objects such as the galaxy clusters in our local neighbourhood.