Convergence and scatter of cluster density profiles

Abstract

We present new results from a series of LCDM simulations of cluster mass halos resolved with high force and mass resolution. These results are compared with recently published simulations from groups using various codes including PKDGRAV, ART, TPM, GRAPE and GADGET. Careful resolution tests show that with 25 million particles within the high resolution region we can resolve to about 0.3% of the virial radius and that convergence in radius is proportional to the mean interparticle separation. The density profiles of 26 high resolution clusters obtained with the different codes and from different initial conditions agree very well. The average logarithmic slope at one percent of the virial radius is $\gamma = 1.26$ with a scatter of $\pm 0.17$. Over the entire resolved regions the density profiles are well fitted by a smooth function that asymptotes to a central cusp $\rho \propto r^{-\gamma}$, where we find $\gamma=1.16\pm 0.14$ from the mean of the fits to our six highest resolution clusters.