Infalling Gas toward the Galactic Center

VLA maps of ammonia emission were made for the Galactic Center region. TheNH3(1,1) and NH3(2,2) transitions were observed in three 2' x 2' fieldscovering Sgr A* and the region 3' immediately south of it. In the central 3parsecs surrounding Sgr A* we find emission which appears to be associated withthe circumnuclear disk (CND), both morphologically and kinematically. Thiscentral emission is connected to a long, narrow 2 pc x 10 pc streamer of clumpymolecular gas located towards the south, which appears to be carrying gas fromthe nearby 20 km/s giant molecular cloud (GMC) to the circumnuclear region. Wefind a velocity gradient along the streamer, with progressively highervelocities as the gas approaches Sgr A*. The streamer stops at the location ofthe CND, where the line width of the NH3 emission increases dramatically. Thismay be the kinematic signature of accretion onto the CND. The ratio of theNH3(2,2)/NH3(1,1) emission indicates that the gas is heated at the northern tipof the streamer, located inside the eastern edge of the CND. The morphology,kinematics and temperature gradients of the gas all indicate that the southernstreamer is located at the Galactic Center and is interacting with thecircumnuclear region.Comment: 11 pages, 10 figures, accepted by The Astrophysical Journal (figure 1 contours have been corrected