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This simulation is good for

  • Modelling galaxies with stellar mass between ~108.5 Msun and the knee of the mass function
  • Running tests for Box-type data products


This simulation carries the same cosmology and resolution as the full Millennium simulation, but is simply a smaller periodic box.  Semi-analytic models are typically calibrated on smaller versions of simulations, like Mini-Millennium, before the full simulation catalogues are produced.  Mini-Millennium is recommended for those who want to quickly sample data products from TAO.  The smaller data volume is much easier to handle for testing pipelines, and results concerning galaxies (with the exception of those in massive clusters) should be representative of the larger simulation.



Box length: 62.5h-1 cMpc

Relative volume to Millennium and an all-sky survey out to z=0.05:

Particle mass: 8.6 × 108h-1 Msun
Gravitational softening: 5h-1 ckpc
Number of particles: 2703
Number of snapshots to z=0: 64

Particle size compared to Millennium:

The mass resolution of Millennium and Mini-Millennium are identical.


The cosmological parameters of the Mini-Millennium simulation are based on WMAP-1 data (Spergel et al. 2003) and the 2dF Galaxy Redshift Survey (Colless et al. 2001).

ΩM = 0.25
ΩΛ = 0.75
Ωb = 0.045

σ8 = 0.9
n = 1
h = 0.73


Haloes and subhaloes were identified using the popular SUBFIND code.  The merger trees of these haloes were subsequently built using LHALOTREE, which is described in the Supplementary Information of the Millennium paper.  (Sub)Haloes required a minimum of 20 particles to be included in the trees.

Semi-analytic galaxies

Galaxy catalogues for the Mini-Millennium simulation available on TAO have been built with the following semi-analytic models:

Dark Sage