Giant molecular clouds contain dense clumps and filamentary structures that serve as crucial nurseries of stars and star cluster. To understand the channeling of material from parsec scales to individual stars within these structures, we aim to characterize key gas properties like density, temperature, and particularly the chemical composition across all scales in molecular clouds. For this purpose, we present the non-equilibrium abundances of various molecules so far unexplored in 3D-MHD simulations. For this, we chemically post-process tracer particles modeled in the SILCC-Zoom simulations with a novel astrochemistry pipeline from Panessa et al. 2023. We use the publicly available network from the astrochemical database KIDA, which includes over 8000 reactions and 557 species.
By analyzing the time evolution and spatial distribution of molecular abundances, we report for the first time detailed formation time-scales and formation regions of various dense-gas tracers like CS, SO, HCN, HNC and N2H+. This allows us in an unprecedented way to test their ability as “internal clocks” for cloud evolution/age under dynamically changing conditions, which is only enabled due to the non-equilibrium chemical modeling applied in this work.
Furthermore, we explore the HCN-HNC ratio as a potential probe for temperature and other environmental factors, and show with which accuracy the HCN/CO ratio traces dense gas fractions, building on recent observational insights. We extend this novel analysis technique of exploring the chemical properties of the ISM to a wide range of environmental conditions, by varying factors such as gas metallicity and the UV and cosmic ray flux. This can provide invaluable input for analyzing and interpreting modern observations of the ISM in various environments.