History independent tracers

We produce a list of molecular species for which the gas history can be ignored, removing a major modelling complexity. We then determine the best of these species to observe in order to constrain various physical parameters.

We use a large set of chemical models with different chemical histories to determine which species have abundances at 1 MYr which are insensitive to the initial conditions. We then use radiative transfer modelling to produce the intensity of every transition of these molecules. We finally compute the mutual information between the physical parameters and all transitions and transition ratios in order to rank their usefulness in determining the value of a given parameter.