GASDYNAMICAL APPROACH TO A FACE-ON VIEW OF THE MILKY-WAY

Analyses of the distribution of far-infrared point sources in the Gala ctic bulge have suggested that from a face-on perspective the bulge ha s a barlike shape. Here, we investigated how a rotating barlike bulge affects the global gasdynamics in a disk and compare the longitude-vel ocity (LV) maps from self-gravitating hydrodynamical simulations with observed maps of neutral. hydrogen and carbon monoxide in the Galaxy. We found that the features on the numerical LV maps depend strongly on four factors: the pattern speed of the bar, the position angle of the Sun, the strength of the bar potential, and the ratio of the gas mass to total dynamical mass. We conclude that our Galaxy has a rotating, weak, barlike bulge observed from nearly end-on. The allowed range of pattern speed of the bar is surprisingly narrow and is consistent with recent observations of bulge stars. Self-gravity of the interstellar matter is needed to account for some of the observations.