We study velocity moments of elliptical galaxies in the Coma cluster using Jeans equations .
The dark matter distribution in the cluster is modelled by a generalised formula based upon the results of cosmological N -body simulations .
Its inner slope ( cuspy or flat ) , concentration , and mass within the virial radius are kept as free parameters , as well as the velocity anisotropy , assumed independent of position .
We show that the study of line-of-sight velocity dispersion alone does not allow to constrain the parameters .
By a joint analysis of the observed profiles of velocity dispersion and kurtosis we are able to break the degeneracy between the mass distribution and velocity anisotropy .
We determine the dark matter distribution at radial distances larger than 3 % of the virial radius and we find that the galaxy orbits are close to isotropic .
Due to limited resolution , different inner slopes are found to be consistent with the data and we observe a strong degeneracy between the inner slope \alpha and concentration c : the best-fitting profiles have the two parameters related with c = 19 - 9.6 \alpha .
Our best-fitting NFW profile has concentration c = 9 , which is 50 % higher than standard values found in cosmological simulations for objects of similar mass .
The total mass within the virial radius of 2.9 h _ { 70 } ^ { -1 } Mpc is 1.4 \times 10 ^ { 15 } h _ { 70 } ^ { -1 } M _ { \sun } ( with 30 % accuracy ) , 85 % of which is dark .
At this distance from the cluster centre , the mass-to-light ratio in the blue band is 351 h _ { 70 } solar units .
The total mass within the virial radius leads to estimates of the density parameter of the Universe , assuming that clusters trace the mass-to-light ratio and baryonic fraction of the Universe , with \Omega _ { 0 } = 0.29 \pm 0.1 .