Structure of Dark Matter Halos from Hierarchical Clustering. III. Shallowing of the Inner Cusp

We investigate the structure of the dark matter halo formed in the cold darkmatter scenarios by N-body simulations with parallel treecode on GRAPE clustersystems. We simulated 8 halos with the mass of $4.4\times 10^{14}M_{\odot}$ to$1.6\times 10^{15}M_{\odot}$ in the SCDM and LCDM model using up to 30 millionparticles. With the resolution of our simulations, the density profile isreliable down to 0.2 percent of the virial radius. Our results show that theslope of inner cusp within 1 percent virial radius is shallower than -1.5, andthe radius where the shallowing starts exhibits run-to-run variation, whichmeans the innermost profile is not universal.Comment: 26 pages, 16 fugures, submitted to Ap