Xinyue Liang (China)
Small-scale processes of star formation and feedback
The small-scale processes of star formation and feedback are tightly linked to galaxy evolution through a multi-scale matter cycle. During this cycle, stars form from the interstellar medium (ISM), and reshape it by injecting energy, momentum and metals, completing a feedback loop. The duration and the efficiency of the successive stages of this cycle vary across and within galaxies, but the exact physical mechanisms driving it remain elusive. A detailed understanding of the small-scale mechanisms regulating star formation and feedback is the key for a full comprehension of galaxy evolution. Increasingly detailed ISM models and multi-wavelength observations now enable us to build a comprehensive view of this multi-scale cycle. As our nearest neighbor, the Large Magellanic Cloud (LMC) has been observed in a broad range of wavelengths and offers the perfect combination between high spatial resolution and a large field of view. It is the ideal laboratory to examine in detail the interplay between stellar activity and the ISM.
I am working on a detailed study of the multi-phase ISM of the LMC using multi-wavelength tracers, tracing all phases of the ISM, from the ionised to the molecular gas. By using MULTIGRIS, a new Bayesian code designed to constrain multi-component ionization models, I have determined key physical parameters of HII regions (e.g., density, ionization parameters, escape fractions of ionizing photons). Leveraging high spatial resolution observations of the LMC, we are now able to connect, for the first time, the multi-phase ISM structure of individual regions with their evolutionary timeline. This enables us to characterize the mechanisms driving star formation and feedback as a function of the local physical properties. Understanding how the detailed physical processes driving this cycle on ~10pc scales regulate the global, galactic-scale properties will serve as a major reference for high-redshift galaxy studies, where spatial resolution is far more limited.
Supervisor: Melanie Chevance (ITA)