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Thursday 29 Sep 2022[Journal Club] - How does stellar feedback in star-forming regions depend on environment?

Ahmad Ali - University of Exeter

4th floor interaction area 11:00-11:45

The thermodynamics of star-forming molecular clouds is set by O stars via stellar feedback processes including photoionization, stellar winds, and radiation pressure. However, the relative roles of each mechanism remain uncertain, especially as a function of the environment (e.g. galactic position or metallicity).

We simulate these mechanisms by coupling a state-of-the-art Monte Carlo radiative transfer scheme with hydrodynamics in 3D, including dust absorption/re-emission and scattering. We investigate how gas metallicity affects the relative strengths of ionization and radiation pressure in isolated star-forming clouds. We show how photoionization is an efficient mechanism for gas expulsion, with HII regions growing faster in lower metallicity clouds. We also present the conditions in which radiation pressure can dominate over thermal pressure from ionized gas. 

To investigate how feedback evolves in non-isolated clouds, we extract cloud complexes from MW-like galaxy evolution models (e.g. Dobbs et al. 2013, Pettitt et al. 2020) and re-simulate at higher resolution. These zoom-ins include ray-traced photoionization and stellar wind methods which are more accurate than is possible on the global galactic scale. They retain the galactic potentials present in the original model, as well as shear/tidal forces which arise between cloud-cloud interactions. This allows us to probe the effect of feedback on gas dispersal and cluster formation in and between many clouds in different environments, such as spiral arm, inter-arm, and bar regions.

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