  The baryon fraction of galaxy clusters in numerical simulations is found to
be dependant on the cluster formation method. In all cases, the gas is
anti-biased compared with the dark matter. However, clusters formed
hierarchically are found to be more depleted in baryons than clusters formed
non-hierarchically. There is a depletion of 10 to 15% for hierarchically formed
clusters while the depletion is less than 10% for those clusters formed
non-hierarchically. This difference is dependent on the mass of the clusters.
The mean baryon enrichment profile for the hierarchically formed clusters shows
an appreciable baryon enhancement around the virial radius not seen in the
clusters formed without substructure. If this phenomenon applies to real
clusters, it implies that determinations of the baryon fractions in clusters of
galaxies require data extending beyond the virial radius of the clusters in
order to achieve an unbiased value.
