Properties of Galaxy Clusters in Cosmologies with Dark Energy

We study the concentration parameters, their mass dependence and redshift evolution, of dark-matter halos in different dark-energy cosmologies with constant and time-variable equation of state, and compare them with "standard" ΛCDM and OCDM models. The dependence of averaged halo concentrations on mass and redshift permits a simple fit of the form (1+z)c=c0(M/M0)α, with α≈-0.1 throughout. We find that the cluster concentration depends on the dark energy equation of state at the cluster formation redshift zcoll through the linear growth factor D+(zcoll). As a simple correction accounting for dark-energy cosmologies, we propose scaling c0 from ΛCDM with the ratio of linear growth factors, c0→c0D+(zcoll)/D+,ΛCDM(zcoll).