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Index - ... - Scientific Goals - Simulations (1/3) - Simulations (2/3) - ...
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4.1 - The 3D cluster distribution
In order to produce an accurate estimate of the cluster distribution
that this survey should observe, we have used the Hubble Volume
simulations performed by the
Virgo
consortium. These simulations examined a sufficiently large region
of space (2-3 gigaparsecs) with enough resolution that we can directly
measure the masses and distributions of simulated clusters. As part of
that work, the distribution of particles was recorded on the past light
cone of an observer at z = 0.
Using the cluster catalogue extracted from these
Hubble Volume
Lightcone Simulations, we have computed survey wedge diagrammes for
2 cosmologies: 
CDM (lambda-dominated
universe)
and 
CDM (critical density universe).
We have applied the survey selection function using the appropriate
L(z)-T-M relations. Results are presented in Fig. 3, 4, 5 & 6.
Since open cosmologies are currently favored by (among others observations)
the non-evolution of the galaxy cluster X-ray luminosity function out
to z ~ 0.8, we have computed the expected correlation function
from the simulated cluster population obtained for the
CDM model (Fig. 4). Results are
presented in Fig. 7 & 8.
Given these results, we conclude that it will be possible to measure the correlation length with a high degree of accuracy in 2 redshift bins.
(Note that owing to observed lack of evolution of the cluster luminosity
function out to z ~ 0.8, there may be even less evolution than
predicted by the CDM model.)
CDM model from the Hubble Volume
Simulation Lightcone for a 8 x 8 sq.deg area (the opening angle of the
wedge has been blown up, for display purpose). One sees clearly the effect
of evolution beyond z > 1: fewer massive clusters are present.
The number of clusters in the 0 < z < 0.4 and
0.4 < z < 1 redshift bins are indicated in brackets.
Cosmological parameters:
0 = 0.3,
= 0.7,
h = 0.7.
CDM cosmology: evolution is much
stronger for this high density universe. Cosmological parameters:
0 = 1,
= 0,
h = 0.5.
CDM cosmology.
CDM model, with the survey
selection function (see Fig.4 - the number of objects are given in that
figure). The line shows the best fit for
=
(r/r0)
.
Associated error ellipses on the correlation length and the exponent
(significance levels: 68.3% (1 d.o.f.), 68.3%. (2 d.o.f.), 99%. (1 d.o.f.).
The simulations show that it will be possible to measure r0
with an accuracy better than 10%.
4.2 - Simulated XMM images of cosmic filaments