Speaker
Description
Nearby galaxies observed at high spatial resolution with JWST, ALMA, and MUSE allow us to address fundamental questions related to the influence of young stars on their surrounding interstellar medium (ISM), from cloud to galactic scales: How far can ionizing photons travel, and what physical mechanisms favor their escape from HII regions? How do such processes shape the ISM and influence galactic evolution?
I will first present constraints on the timescales and physical mechanisms associated with the evolutionary cycle of molecular clouds in 30 galaxies from the PHANGS-JWST survey, including their dust-embedded star formation phase. We find that the embedded phase of star-formation is typically short (< 4 Myr) and is drastically reduced in late-type galaxies. Strikingly, this phase seems absent in galaxies with a relatively metal-poor ISM, that may host different populations of HII regions, possibly associated with ionizing photon leakage.
To further investigate the physics at play in such environments, I will present results obtained on a sample of 13 resolved dwarf galaxies observed with MUSE, extending the metallicity range probed by PHANGS. Using multicomponent models to interpret their spectral data, we infer the main physical properties of their HII regions, including the escape fraction of ionizing photons, and assess how the local porosity to UV photons may affect the ISM at larger scales.
