Monday

The ultraviolet radiation emitted by young, massive stars can have a huge impact on the surrounding environment. This radiation affects the chemistry of the interstellar medium (ISM) as it destroys molecules and ionises the interstellar gas, while the heat injected by the radiation creates a hot bubble that can inhibit further star formation. Modelling the effects of stellar radiation on the ISM is therefore important for understanding how it can regulate ongoing star formation, and for interpreting a wide range of ISM emission and absorption line diagnostics. However, following the full 3D radiative transfer of stellar radiation in galaxy simulations can be computationally expensive. In this talk, I will present a suite of simulations of isolated disc galaxies, from dwarfs to Milky Way-mass galaxies, in which we couple an approximate treatment for the stellar radiation from individual star particles to a time-dependent chemical model that follows the evolution of 157 ions and molecules. I will compare these to simulations in which we assume a uniform interstellar radiation field, to demonstrate how the inclusion of a local treatment for stellar radiation affects the evolution of the galaxy, the properties of the multiphase ISM, and observable ISM line diagnostics. I will also use these simulations to show how ISM line diagnostics trace the physical conditions of the ISM, which is important for interpreting observations of these lines.