Spectral imaging of the Sagittarius B2 region in multiple 3-mm molecular lines with the Mopra telescope

Jones, P.A., Burton, M.G., Cunningham, M.R., Menten, K.M., Schilke, P., Belloche, A., Leurini, S., Ott, J., and Walsh, A.J. (2008) Spectral imaging of the Sagittarius B2 region in multiple 3-mm molecular lines with the Mopra telescope. Monthly Notices of the Royal Astronomical Society, 386 (1). pp. 117-137.

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Using the Mopra telescope, we have undertaken a 3-mm spectral-line imaging survey of a 5 × 5 arcmin2 area around Sgr B2. We covered almost the complete spectral range from 81.7 to 113.5 GHz, with 2.2 MHz wide spectral channels or ∼6 km s −1 and have observed 24 lines, with 0.033 MHz wide, or ∼0.1 km s −1 channels. We discuss the distribution of around 50 lines, and present velocity-integrated emission images for 38 of the lines. In addition, we have detected around 120 more lines, mostly concentrated at the particularly spectral-line-rich Sgr B2(N) source.

There are significant differences in molecular emission, pointing to both abundance and excitation differences throughout the region. Seven distinct spatial locations are identified for the emitting species, including peaks near the prominent star-forming cores of Sgr B2(N), (M) and (S) that are seen in infrared (IR)-to-radio continuum images. The other features are a 'north ridge' and a 'north cloud' to the north of the Sgr B2 N-M-S cores, a 'south-east peak' and a 'west ridge'.

The column density, as evident through C18O, peaks at the Sgr B2(N) and (M) cores, where strong absorption is also evident in otherwise generally bright lines such as HCO+, HCN and HNC. Most molecules trace a ridge line to the west of the Sgr B2 N-M-S cores, wrapping around the cores and extending north-east to the north cloud. This is most clearly evident in the species HC3N, CH3CN, CH3OH and OCS. They are found to be closer in distribution to the cooler dust traced by the submillimetre continuum than either the warmer dust seen in the mid-IR or to the radio continuum. The molecule CN, in contrast, is reasonably uniform over the entire region mapped, aside from strong absorption at the positions of the Sgr B2(N) and (M) cores.

Item ID: 7105
Item Type: Article (Research - C1)
ISSN: 1365-2966
Keywords: ISM: individual; Sagittarius B2; ISM: kinematics and dynamics; ISM: molecules; radio lines: ISM
Date Deposited: 23 Mar 2010 03:33
FoR Codes: 02 PHYSICAL SCIENCES > 0299 Other Physical Sciences > 029999 Physical Sciences not elsewhere classified @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970102 Expanding Knowledge in the Physical Sciences @ 100%
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