Description
The Sagittarius B2 (SgrB2) molecular cloud is a well-known region of high-mass star formation close to the Galactic Center. Its hot molecular core SgrB2 (M) contains at least 36 HII regions and 12 sub-mm cores. A full line survey of SgrB2 (M) has been obtained using the HIFI spectrometer aboard of the Herschel Observatory as part of the guaranteed-time key-project "Herschel/HIFI Observations of EXtraOrdinary Sources: The Orion and Sagittarius B2 Starforming Regions"(HEXOS, PI: E. Bergin, U. Michigan).
We determine the physical structure of SgrB2(M) using continuum maps for the density structure and selected molecular line spectra and maps (CO, HCN, their isotopologues and in the case of HCN also the vibrationally excited lines) for the kinematic gas properties. HCN serves as a tracer of the innermost temperature and velocity field. In that approach, the HIFI SgrB2(M) survey provides the necessary variety both in molecules and covered frequency range and ancillary SMA interferometric data adds the necessary spatial resolution
We employ a detailed three-dimensional radiative transfer modelling approach that includes a self-consistent determination of the dust temperature. The former is calculated using LIME (Brinch), the latter using RADMC-3D (developped by C. Dullemond). With this toolkit, we are able to make dust continuum images as well as spectral line cubes. The maps are convolved with the uv-coverage or beam of the observations for comparison reasons.
In the case of SgrB2(M), we are able to reproduce the continuum covering the frequency range from ~300 GHz to 2000 GHz. In order to reproduce the line strength of the CO transitions, we need to raise the gas temperature in the center of the the hot molecular core over the dust temperature suggesting the presence of shocks.
Author
Anika Schmiedeke
(Universität zu Köln)