Profiles of dark-matter haloes at high redshift

I study the evolution of haloes density profiles as a function of time in the SCDM and ΛCDM cosmologies. Following Del Popolo et al. (1999), I calculate the concentration parameter c = rv/a and study its time evolution. For a given halo mass, I find that c(z) ∝ 1/(1 + z) both in the ΛCDM and SCDM cosmology, in agreement with Bullock et al. (1999) analytic model and N-body simulations. In both models, a(z) is roughly constant. The present model predicts a stronger evolution of c(z) with respect to Navarro et al. (1997) (hereafter NFW97) model. Finally I show some consequences of the result on galaxy modelling.