Paper detail

Properties of galaxy clusters in N-body simulations: Intrinsic properties

We study the influence of the various parameters of scenarios of large-scale structure formation on properties of galaxy clusters, and investigate which cluster properties are most sensitive to these parameters. We present a set of large N-body simulations and derive the intrinsic properties of galaxy clusters in these simulations, which represent a volume of $256^3 h^{-3}$ Mpc^3. The cosmological scenarios studied differ in either the shape of the power spectrum of initial fluctuations, its normalization, the density parameter $Ω_{0}$, or the Hubble parameter $H_{0}$. Between each of the simulations, only one parameter is set differently, so that we can study the influence of that parameter on the cluster properties. The cluster properties that are studied are the mass, line-of-sight velocity dispersion, peculiar velocity, intrinsic shape, and orientation with respect to its surroundings. $σ_{8}$ has a large impact on the cluster properties. The latter, viz. the cluster number density, mass, line-of-sight velocity dispersion and peculiar velocity, are also determined by $Ω_{0}$, though somewhat less. Other parameters, such as $H_{0}$, the tilt of the initial fluctuation spectrum, and the exact shape of this spectrum, are generally less important. Unlike the other cluster properties studied, the peculiar velocity is found to depend on all parameters of the formation scenario. Using scaling relations between the average properties of the cluster sample and the parameters of the formation scenario, one may try and interpolate between the scenarios studied here in order to find the parameters of the scenario that is most consistent with the data.