Numerical study of halo concentrations in dark-energy cosmologies

¹ Dipartimento di Astronomia, Università di Padova, Italy
² Max-Planck-Institut für Astrophysik, PO Box 1317, 85741 Garching, Germany
³ SISSA, Trieste, Italy
⁴ Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
⁵ Dipartimento di Astronomia, Università di Bologna, Italy

Corresponding author: K. Dolag, kdolag@pd.astro.it

Received: 18 August 2003
Accepted: 2 December 2003

Abstract

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. 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 ~0.2. The dependence of averaged halo concentrations on mass and redshift permits a simple fit of the form , with 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 . As a simple correction accounting for dark-energy cosmologies, we propose scaling c₀ from ΛCDM with the ratio of linear growth factors, .