

Introduction: The Millennium Simulation

The Millennium Run used more than 10 billion particles to trace the evolution of the matter distribution in a cubic region of the Universe over 2 billion light-years on a side. It kept busy the principal supercomputer at the Max Planck Society's Supercomputing Centre in Garching, Germany for more than a month. By applying sophisticated modelling techniques to the 25 Tbytes of stored output, Virgo scientists have been able to recreate evolutionary histories both for the 20 million or so galaxies which populate this enormous volume and for the supermassive black holes which occasionally power quasars at their hearts. By comparing such simulated data to large observational surveys, one can clarify the physical processes underlying the buildup of real galaxies and black holes.

Movies of the simulation

A 3-dimensional visualization of the Millennium Simulation. The movie shows a journey through the simulated universe. On the way, we visit a rich cluster of galaxies and fly around it. During the two minutes of the movie, we travel a distance for which light would need more than 2.4 billion years.

Get this movie in different versions:

Fast flight [divx5, 60 MB, 1024x768]

Slow flight [divx5, 120 MB, 1024x768]

Credit: Springel et al. (2005)

The movies below shows the dark matter distribution in the universe at the present time, based on the Millennium Simulation, the largest N-body simulation carried out thus far (more than 1010 particles). By zooming in on a massive cluster of galaxies, the movie highlights the morphology of the structure on different scales, and the large dynamic range of the simulation (105 per dimension in 3D). The zoom extends from scales of several Gpc down to resolved substructures as small as ~10 kpc.

Get this movie in different resolutions:

Pictures of the galaxy distribution

The top row of the following pictures shows the galaxy distribution in the simulation, both on very large scales, and for a rich cluster of galaxies where one can see them individually. The top right panel hence represents the large-scale light distribution in the Universe. For comparison, the images in the lower row give the corresponding dark matter distributions.



Click to enlarge the images.





Slices of the dark matter distribution

The following poster shows a projected density field for a 15 Mpc/h thick slice of the redshift z=0 output. The overlaid panels zoom in by factors of 4 in each case, enlarging the regions indicated by the white squares. Yardsticks are included as well. The postscript file has been produced for A0 format. Beware of it's huge size.

The following slices through the density field are all 15 Mpc/h thick. For each redshift, we show three panels. Subsequent panels zoom in by a factor of four with respect to the previous ones.





Halo and semi-analytic galaxy catalogues

Together with a paper by Croton et al. (2005), a first set of semi-analytic catalogues has been made available. Follow this link for a download page.

In these catalogues, galaxy magnitudes are available in both BVRIK (Vega) or ugriz (AB SDSS) filters. The catalogues only include galaxies above our magnitude completeness limit (-17.4 in r (SDSS) and -16.4 in B), for a total of about 9 million galaxies in the full simulation box (500 Mpc/h on a side). The galaxies are stored as either a binary structure (~620 Mb, IDL script available) or in ASCII format (~980 Mb). A "mini" version of the catalogue is also available for testing purposes (<2 Mb), which is identical in every way to the full version but in a smaller periodic box of 62.5 Mpc/h on a side.



Recently, the full Millennium semi-analytic catalogue at all redshifts, together with the complete dark matter merging history trees, has been made publicly available. This release has been announced on astro-ph by Lemson et al. (2006), and this page describes the data products available and where and how they can be accessed. The data can be studied with a powerful SQL-query interface that is oriented along the concept of a Virtual Astronomical Obervatory.

References

Simulations of the formation, evolution and clustering of galaxies and quasars

Volker Springel, Simon D. M. White, Adrian Jenkins, Carlos S. Frenk, Naoki Yoshida, Liang Gao, Julio Navarro, Robert Thacker, Darren Croton, John Helly, John A. Peacock, Shaun Cole, Peter Thomas, Hugh Couchman, August Evrard, Joerg Colberg & Frazer Pearce, 2005, Nature, 435, 629 The age dependence of halo clustering

Liang Gao, Volker Springel, Simon D. M. White, 2005, MNRAS, in press The many lives of AGN: cooling flows, black holes and the luminosities and colours of galaxies

Darren J. Croton, Volker Springel, Simon D. M. White, G. De Lucia, C. S. Frenk, L. Gao, A. Jenkins, G. Kauffmann, J. F. Navarro, N. Yoshida, 2005, MNRAS, submitted The cosmological simulation code GADGET-2

Volker Springel, 2005, MNRAS, submitted Supercomputer Simulations Explain the Formation of Galaxies and Quasars in the Universe

Max-Planck Society, 2005, Press Release The largest N-body simulation of the universe

Volker Springel, 2004, MPA research highlight article

Comments to: Virgo Administrator virgo@mpa-garching.mpg.de