The Flattened Dark Matter Halos of Ngc 4244 and the Milky Way A

In a previous paper a method was developed to determine the shapes of dark matter halos of spiral galaxies from the flaring and velocity dispersion of the gas layer. Here I present the results for the almost edge-on Scd galaxy NGC 4244 and preliminary results for the Milky Way. NGC 4244’s dark matter halo is found to be highly flattened with a shortest-to-longest axis ratio of 0.2 −0.1 . If the dark matter is disk-like, the vertical velocity dispersion of the dark matter must be ∼ 20% larger than the measured tangential dispersion in the H I . The flaring of the Milky Way’s gas layer, the local column of identified stars and the total column within 1.1 kpc from the plane are consistent with a moderately flattened dark halo (E7-E0) and galactic constants of R0 = 7.1 kpc, Θ0 = 180 km s , while the stellar disk is ∼ 80% of maximal.