Gas as a Tracer of the Galactic Potential

Abstract

We consider a disk-like dark matter model for the Milky Way and compare a few predictions with observations. The observed gaseous flaring for HI and molecular gas fits the model predictions in detail. The global HI distribution in the Milky Way needs to be explained by a multiphase medium. The dark matter distribution in the Galactic halo is traced by a low density component of halo gas. High-velocity clouds with distances up to ∼ 50 kpc may be explained as condensations which originate from instabilities within the gaseous halo. Our model explains also ‘beards’ and ‘forbidden velocities’ as observed in the rotation curves of external galaxies. A disk-like dark matter model is self-consistent and in excellent agreement with observations.