Multiplicity of nuclear dust lanes and dust lane shocks in the Milky Way bar

摘要

Aims: We show the existence of a small family of inner-galaxy dust lanes anddust lane standing shocks beyond the two major ones that were previously knownto exist Methods: We analyze images of CO emission in the inner regions of theGalaxy Results: The peculiar kinematics of the major dust lane features arerepeated in several other distinct instances at l > 0deg, in one case at acontrary location 100 pc above the galactic equator at l > 3degr at the upperextremity of Clump 2. Like the previously-known dust lanes, these new examplesare alsoassociated with localized, exceptionally broad line profiles believedto be characteristic of the shredding of neutral gas at the standing dust laneshocks. Conclusions: There may be secondary dust lane and standing shocks inthe Milky Way bulge. The vertical structure provides a temporal sequence forunderstanding the secular evolution of gas flow in the bar.