A radio survey of Galactic center clouds

We present a radio survey of molecules in a sample of Galactic center molecular clouds, including M0.25 + 0.01, the clouds near Sgr A, and Sgr B2. The molecules detected are primarily NH₃ and HC₃N; in Sgr B2-N we also detect non-metastable NH₃, vibrationally-excited HC₃N, torsionally-excited CH₃OH, and numerous isotopologues of these species. 36 GHz Class I CH₃OH masers are ubiquitous in these fields, and in several cases are associated with new NH₃ (3,3) maser candidates. We also find that NH₃ and HC₃N are depleted or absent toward several of the highest dust column density peaks identified in submillimeter observations, which are associated with water masers and are thus likely in the early stages of star formation.