Gas dynamics in the Milky Way: second pattern speed and large-scale morphology

Abstract

We present new gas flow models for the Milky Way inside the solar circle. We use smoothed particles hydrodynamics (SPH) simulations in gravitational potentials determined from the near-infrared (NIR) luminosity distribution of the bulge and disc, assuming a constant NIR mass-to-light ratio, with an outer halo added in some cases. The luminosity models are based on the COBE/DIRBE maps and on clump giant star counts in several bulge fields and include a spiral arm model for the disc.