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

National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475, USA e-mail: hliszt@nrao.edu

Received: 8 March 2008
Accepted: 18 May 2008

Abstract

Aims. We show the existence of a small family of inner-galaxy dust lanes and dust lane standing shocks beyond the two major ones that were previously known to exist

Methods. We analyze images of CO emission in the inner regions of the Galaxy

Results. The peculiar kinematics of the major dust lane features are repeated in several other distinct instances at l > 0°, in one case at a contrary location 100 pc above the galactic equator at l > 3°at the upper extremity of Clump 2. Like the previously-known dust lanes, these new examples are also associated with localized, exceptionally broad line profiles believed to be characteristic of the shredding of neutral gas at the standing dust lane shocks.

Conclusions. There may be secondary dust lane and standing shocks in the Milky Way bulge. The vertical structure provides a temporal sequence for understanding the secular evolution of gas flow in the bar.