Are the 2dFGRS superstructures a problem for hierarchical models?

Understand

We introduce an objective method to assess the probability of finding extreme events in the distribution of cold dark matter such as voids, overdensities or very high mass haloes.

• Our approach uses an ensemble of N-body simulations of the hierar- chical clustering of dark matter to find extreme structures.
• The frequency of extreme events, in our case the cell or smoothing volume with the highest count of cluster-mass dark matter haloes, is well described by a Gumbel distribution.
• This distribution can then be used to forecast the probability of finding even more extreme events, which would otherwise require a much larger ensemble of simulations to quantify.