7–11 Jul 2025
Teaching and Learning Centre (TLC)
Europe/London timezone

Emission line diagnostics in H II regions: a non-equilibrium perspective

7 Jul 2025, 16:40
15m
TLC113

TLC113

Talk Star formation across environments: From individual molecular clouds to entire galaxies Star formation across environments: From individual molecular clouds to entire galaxies

Speaker

Yuankang Liu (Durham University)

Description

Recent advancements in instrumentation have enabled the investigation of star-forming regions in nearby galaxies with unprecedented spatial resolution. To facilitate detailed comparisons between simulations and observations, we generate mock emission line maps based on a state-of-the-art simulation of an ideal H II region, utilizing a novel post-processing pipeline. This simulation couples radiation hydrodynamics (SWIFT-RT) with a non-equilibrium photochemistry network (CHIMES), incorporating 157 chemical species.
In this talk, I will introduce a new atomic model that accurately predicts hydrogen recombination line emissivity. This model is computationally efficient and can be seamlessly integrated into post-processing workflows for hydrodynamic simulations. By applying it to our new simulation, we gain new insights into emission line diagnostics in a non-equilibrium setting, which was previously unattainable. I will then explore widely used diagnostic tools in the ISM community, highlighting their deviations from traditional equilibrium-based predictions.
Our new atomic model and post-processing pipeline significantly enhance our ability to study emission line diagnostics from a non-equilibrium perspective. The atomic model, together with the pipeline, steps towards bridging the gap between simulations and observations, providing insights into the physical conditions of star-forming regions and contributing to the refinement of theoretical models.

Author

Yuankang Liu (Durham University)

Co-authors

Prof. Tom Theuns (Durham University) Alex Richings (University of Hull) Dr Tsang Keung Chan (Chinese University of Hong Kong) Dr Anna McLeod (Durham University)

Presentation materials