We establish the presence of a dark matter core radius, for the first time in a very large number of spiral galaxies of all luminosities. Contrary to common opinion we find that the sizes of these cores and the " DM core problem" are bigger for more massive spirals. As a result the Burkert profile provides an excellent mass model for dark halos around disk galaxies. Moreover, we find that the spiral dark matter core densities $\rho_{ 0}$ and core radii $r_{ 0}$ lie in the same scaling relation $\rho_{ 0}=4.5\times 10^-2 (r_{ 0}/kpc)^{ -2/3} M_{ \odot}pc^{ -3}$ of dwarf galaxies with core radii upto ten times more smaller.
Categories: astro-ph