Dense Gas Toolbox – This is for all radioastronomers out there!

I am happy to announce that the first online version of the Dense Gas Toolbox (DGT) is now available. DGT allows to derive gas densities and temperatures from observed molecular lines. The toolbox contains a novel set of radiative transfer models which take into account that observed molecular line intensities usually arise from a multi-density gas rather than from a single zone. Hence, the models allow for more realistic interpretations (in terms of gas density and temperature) of observed molecular lines.

The models build up upon RADEX, i.e. they use non-LTE LVG (expanding sphere) escape probabilities and molecular data from the Leiden Atomic and Molecular Database.

The models were calibrated using data of the EMPIRE survey, i.e. the abundances and line optical depths are fixed based on observations of local star-forming disk galaxies. In the current version (v1.2) of DGT the following rotational transitions are implemented in the frequency range between ~88 and ~345GHz:

• ¹²CO (up to J=3)
• ¹³CO (up to J=3)
• C¹⁸O (up to J=3)
• C¹⁷O (up to J=3)
• HCN (up to J=3)
• HNC (up to J=3)
• HCO+ (up to J=3)