We perform a series of high – resolution N-body simulations designed to examine the density profiles of dark matter halos .
From 12 simulated halos ranging the mass of 2 \times 10 ^ { 12 } \sim 5 \times 10 ^ { 14 } h ^ { -1 } { M _ { \odot } } ( represented by \sim 1 million particles within the virial radius ) , we find a clear systematic correlation between the halo mass and the slope of the density profile at 1 % of the virial radius , in addition to the variations of the slope among halos of the similar mass .
More specifically , the slope is \sim - 1.5 , -1.3 , and -1.1 for galaxy , group , and cluster mass halos , respectively .
While we confirm the earlier simulation results that the inner slope is steeper than the universal profile originally proposed by Navarro , Frenk & White , this mass dependence is inconsistent with the several analytical arguments attempting to link the inner slope with the primordial index of the fluctuation spectrum .
Thus we conclude that the dark matter density profiles , especially in the inner region , are not universal .