Paper  astro-ph/0504097

Simulating the joint evolution of quasars, galaxies and their large-scale distribution

The cold dark matter model has become the leading theoretical paradigm for the formation of structure in the Universe. Together with the theory of cosmic inflation, this model makes a clear prediction for the initial conditions for structure formation and predicts that structures grow hierarchically through gravitational instability. Testing this model requires that the precise measurements delivered by galaxy surveys can be compared to robust and equally precise theoretical calculations. Here we present a novel framework for the quantitative physical interpretation of such surveys. This combines the largest simulation of the growth of dark matter structure ever carried out with new techniques for following the formation and evolution of the visible components. We show that baryon-induced features in the initial conditions of the Universe are reflected in distorted form in the low-redshift galaxy distribution, an effect that can be used to constrain the nature of dark energy with next generation surveys.

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(See also: Download site for full halo and semi-analytic galaxy catalogues)

This movie 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.		High-res, no annotation [mpeg4, 47.6 MB, 1920x1080] High Quality [mpeg4, 52.1 MB, 1024x768] High Quality [divx5, 48.6 MB, 1024x768] Medium Quality [divx5, 13.4 MB, 640x480] Low Quality [divx5, 10.8 MB, 512x384] Slow Zoom [divx5, 165.6 MB, 1024x768] The video data is compressed using divx5 (MPEG4) and has fairly high resolution, such that a fast PC and a good graphics card are required to play them properly. To this end, you can use the 'mplayer' program under Linux. On a Mac, 'quicktime' should work once the divx-codec is installed, available free of charge here. Likewise for `windows mediaplayer'.

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.		Fast high-res flight [mpeg4, 150 MB, 1920x1080] Fast flight [divx5, 60 MB, 1024x768] Slow flight [divx5, 120 MB, 1024x768] Credit: Springel et al. (2005)

The top row of these 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.

The 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! [768x1024]  [1536x2048]  [poster.ps.gz, A0, 280 MB]

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. Redshift z=0 (t = 13.6 Gyr)
[1024x768] [2048x1536] [plain]	[1024x768] [2048x1536] [plain]	[1024x768] [2048x1536] [plain]
Redshift z=1.4 (t = 4.7 Gyr)
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Redshift z=5.7 (t = 1.0 Gyr)
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Redshift z=18.3 (t = 0.21 Gyr)
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