A 3-mm molecular line study of the Central Molecular Zone

Abstract

We are studying the Central Molecular Zone (CMZ) in the inner few degrees around the Galactic Centre, by mapping a large number of 3-mm molecular lines. We have used the 22-m Mopra telescope, with the new capabilities of the 8-GHz bandwidth MOPS digital filter bank. During 2006, we covered a 5 × 5 arcmin2 area of the Sagittarius B2 molecular cloud complex, with spectral coverage of nearly all of the range 81.7 to 113.5 GHz with 4 tunings of the broad band mode. We imaged over 50 spectral lines with strong extended emission and around 110 more lines which were weak, or concentrated at the Sgr B2(N) and Sgr B2(M) cores (Jones et al. 2008). We find substantial differences in chemical and physical conditions within the complex. During 2007 we covered the larger region of longitude -0.2 to 0.9 deg. and latitude -0.20 to 0.12 deg., including Sgr A and Sgr B2, in the frequency range 85.3 to 91.3 GHz. This includes lines of C3 H2 , CH3 CCH, HOCO+ , SO, H13 CN, H13 CO+ , SO, HN13 C, C2 H, HNCO, HCN, HCO+ , HNC, HC3 N, 13 CS and N2 H+ .