New Approach to the Problem of Structure of Spiral Galaxies

A new, alternative approach is proposed to explain the flat velocity spectrum of orbital motion of stars at the periphery of spiral galaxies and, in particular, the significant excess of velocity values calculated according to the virial theorem. The concept consists in the assumption of the presence in the gravitational field of the galaxy of a central body of cylindrical rather than spherical symmetry. This configuration of the field can be explained by the presence along the galactic axis of a cosmic string, whose length overlaps the diameter of the galactic disk. This model will be subjected to comparison with the more traditional concept of the presence in a spiral galaxy of a spherical halo of dark matter. For this approach a kinematic model is also proposed and a hypothesis is enunciated regarding the nature of dark matter. Results of astronomical observations on the presence of cosmic strings in zones adjacent to galaxies are analyzed.