Cosmological solution for the problem of rotation velocities in galaxies

A solution for the problem of understanding observed rotation curves in galaxies without the introduction of dark matter halos is presented. This solution has been obtained upon considering the distribution of masses in the expanding universe, then, having a cosmological character. A formal limiting radius for galaxies depending on cosmological parameters is given. The empirical conclusions derived from the theory of M. Milgrom and J. Bekenstein arise as direct consequences of the present approach without any need of drastically modifying newtonian dynamics.