Dark matter halos 461(a)(b)Figure 15.18.(a) Dependence of concentration with mass for distinct halos. The bold full
curve is the median value. The errors are errors of the mean due to sampling. The outer
chain curves encompass 68% of halos in the simulations. The broken curves and arrows
indicate values corrected for the noise in halo profiles. Thin curves are different analytical
models. (b) Median halo concentration as a function of mass for different redshifts. The
thin lines show the predictions of an analytical model. (After Bullocket al2001.)