Speaker
Description
The outer milky way is an environment with a lower carbon and oxygen content. This influences the formation and survival of molecules during star formation in this region. In this work we try to understand the nonlinearity between the state of the physical environment, including the initial chemical content, of these cold dense gas clouds and the observed ratios of the gas. To this end we use the open-source gas-grain chemistry code UCLCHEM to simulate the evolution of the molecules for a grid of physical parameters. Subsequently we apply Shapley Additive Values (SHAP) to understand not only correlations, but also the higher order nonlinearities of these models. We find that the ratios can posses highly nonlinear behaviour as a function of well known parameters, such as temperature, density and radiation field, but these patterns can become even more complex with varying the carbon and oxygen initial abundance.
