NH3 observations of the Central Molecular Zone with Kagoshima 6 meter radio telescope

Abstract

We made a wide survey in two Ammonia lines of the major part of the Central Molecular Zone in the Galactic center region. The ammonia emission can be detected at most of the observed positions, which means ammonia emission is extended over the Central Molecular Zone. We identify 4 clouds, which correspond Sgr A 20-km s-l cloud, Sgr A 50-km s-1 cloud, sgr B cloud complex, and the 1.3-degree cloud. Besides them diffuse emission can be detected over the Central Molecular Zone. The intensity ratio of the (2,2) transition to (1,1) transition is uniform over most of the observed region and is about 0.7-0.8, which means that the molecular gas is 24-42 K. It means most dense gas in the Galactic center region is as cool as majority of dust there. This cool temperature is consistent to the values derived previously, although their observed coverage was smaller than ours. On l - v plane the NH3 emitting region is surrounded by clouds with the high intensity ratio of CO (2-1) to CO (1-0) lines. It means the dense molecular gas is surrounded by hot molecular gas in 10-100 pc scale. © 2006 IOP Publishing Ltd.