Numerical study of halo concentrations in dark-energy cosmologies

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 ACDM and OCDM models. We find that previously proposed algorithms for predicting halo concentrations can be well adapted to dark-energy models. When centred on the analytically expected values, halo concentrations show a log-normal distribution with a uniform standard deviation of similar to0.2. The dependence of averaged halo concentrations on mass and redshift permits a simple fit of the form (1 + z) c = c(0) (M/M-0)(alpha), with alpha approximate to -0.1 throughout. We find that the cluster concentration depends on the dark energy equation of state at the cluster formation redshift z(coll) through the linear growth factor D+(z(col)). As a simple correction accounting for dark-energy cosmologies, we propose scaling c(0) from ACDM with the ratio of linear growth factors, c(0) --> c(0) D+(z(coll))/D+. (ACDM) (z(coll)).