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-Introduction
-Simulation-   Parameters
-Simulation model comparisons
-References
-Credit

Data Visualization (images & movies from Numerical Simulation projects)

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Introduction: Cosmological N-Body Simulations

Four different cosmological models were simulated in large boxes. The simulations contain 2563 particles each and represent different cosmological models. The calculations were done by the parallel version of the AP3M N-body code on two large Cray T3D parallel supercomputers at the Edinburgh Parallel Computing Center and at the Computing Centre of the Max Planck Society in Garching

Simulation Parameters

Shown in the left panels are projected mass distibutions in a sliced region in the simulation box. Low-density regions which look like "voids" are dark, while red (and yellow) parts are high-density regions. The pictures were created using an adaptive smoothing scheme which assigns to each particle an individual smoothing length. Thus, high density regions are not smoothed at all whereas low density regions are smoothed.

Pictures credit: Joerg Colberg

Boxsize 239.5 Mpc/h
256³ particles
OMEGA = 1.0
LAMBDA = 0.0
H0 = 50 km/(Mpc sec)
Sigma8 = 0.51
Mass per particle 22.7 10¹⁰M_sun/h

A density plot at z=0. The brightness of the colours is proportional to the log of the density of the particles. Note: This GIF picture has a size of 3.4MB!
A mosaic (GIF) which shows several blow ups at z=0.

Lambda CDM

Boxsize 239.5 Mpc/h
256³ particles
OMEGA = 0.3
LAMBDA = 0.7
H0 = 70 km/(Mpc sec)
Sigma8 = 0.9
Mass per particle 6.86 10¹⁰M_sun/h

Density plot at z=0
Blow-up mosaic

Open CDM

Boxsize 239.5 Mpc/h
256³ particles
OMEGA = 0.3
LAMBDA = 0.0
H0 = 70 km/(Mpc sec)
Sigma8 = 0.85
Mass per particle 6.86 10¹⁰M_sun/h

Density plot at z=0
Blow-up mosaic

tau CDM

Boxsize 239.5 Mpc/h
256³ particles
OMEGA = 1.0
LAMBDA = 0.0
H0 = 50 km/(Mpc sec)
Sigma8 = 0.51
Mass per particle 22.7 10¹⁰M_sun/h

Density plot at z=0
Blow-up mosaic

VIRGO Simulations Model Comparisons

The pictures below show projected mass distributions in slices of the Virgo simulation boxes. The first one has 12 panels, 3 different redshifts in a row for each model. Thus in this picture we see the time evolution of structures along the horizontal sequence in each model as well as the model difference at the same epoch along the vertical sequence.
The second picture is a comparison of the 4 models at redshift 0, which is equivalent to a collection of 4 figures in one column in the first picture. The third picture at redshift 1 and the fourth at z=3.

Pictures are downloadable in the original sizes in various format. If you would like to download these pictures,
PLEASE ATTACH THE SUITABLE CREDIT AND REFERENCE GIVEN ON THE BOTTOM OF THIS PAGE.

Comparison of all simulations
gzipped PS format
GIF
JPEG

Comparison at z=0
gzipped PS format
GIF
JPEG

Comparison at z=1
gzipped PS format
GIF
JPEG

Comparison at z=3
gzipped PS format
GIF
JPEG

Suitable references
(Virgo-simulation selected publications):

Evolution of Structure in Cold Dark Matter Universes, A. Jenkins, C.S. Frenk, F.R. Pearce, P.A. Thomas, J.M. Colberg, S.D.M. White, H.M.P Couchman, J.A. Peacock, G. Efstathiou, and A.H. Nelson (The Virgo Consortium), 1998, Astrophysical Journal, 499, 20-40.

The structure of galaxy clusters in various cosmologies, P.A. Thomas, J.M. Colberg, H.M.P Couchman, G. Efstathiou, C.S. Frenk, A. Jenkins, A.H. Nelson, R.M. Hutchinhgs, J.A. Peacock, F.R. Pearce, S.D.M.

Credit

Here is an example of proper credit for these Virgo data.
"The simulations in this paper were carried out by the Virgo Supercomputing Consortium using computers based at Computing Centre of the Max-Planck Society in Garching and at the Edinburgh Parallel Computing Centre. The data are publicly available at www.mpa-garching.mpg.de/galform/virgo/int_sims"

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