Position-Velocity Diagrams as a Probe of the Bar in Edge-On Galaxies

Keiichi Wada, Tetsuo Hasegawa, Yoshiaki Sofue, Yoshiaki Taniguchi, Asao Habe
1996 Symposium - International astronomical union  
Analyses of the distribution of far infrared point sources in the Galactic bulge have suggested that from a face-on perspective the bulge has a bar like shape. Here, we investigate how a rotating bar-like bulge affects the global gas dynamics in a disk and compare the longitude-velocity (LV) maps from selfgravitating 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
more » ... ors: 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, bar-like bulge (a/b ∼0.8) observed from nearly end on (θp< 20°). The allowed range of pattern speed of the bar is surprisingly narrow (∼ 20 km s–1kpc–1) and is consistent with recent observations of bulge stars. Selfgravity of the interstellar matter is needed to account for some of the observations.
doi:10.1017/s007418090022963x fatcat:pg5dep5xjncgndqooob47hkiwe