  A cylindrical model for the dark matter halo of disk galaxies is developed.
At the center of the cylinder, in the plane perpendicular to the long axis, the
rotation curve is constant for distances much less than the cylinder length and
Keplerian at much greater distances. The rotation curve is equivalent to the
spherical truncated flat (TF) profile, a model derived empirically from the
radial velocity dispersion of the Milky Way dark halo. It is shown that an
isothermal, self-gravitating cylinder of length 89 kpc can account for the
observed radial velocity dispersion of the Milky Way dark halo with less mass
than the NFW profile. Moreover, a cylindrical model of the Milky Way dark halo
is consistent with free-streaming neutrinos of mass 1.1 eV.
