Nearby galaxies offer an privileged view of the interstellar medium, with no confusion on objects size and distance. The high resolution and sensitivity of modern telescopes now allow to study the detailed physics of star formation and interstellar matter evolution in remote systems. Our neighbouring galaxies also offer opportunities to study the ISM in vastly different physical conditions (e.g., metallicity, feedback...) than what can be done in the Milky Way. During this meeting we will dive into nearby galaxy studies in order to build a bigger picture of star formation, including the impact of galaxy interactions and circumgalactic matter infall on the overall evolution of baryons.
Understanding galaxy formation and evolution requires to consider gas flows in and around galaxies. The circum-galactic medium (CGM), in particular, is an essential component of a galaxy evolution. Matter falling from the CGM into galaxies provides metal-poor gas that sustains star formation. The ejection of matter in the halo of galaxies by intense star formation activity (the so-called Galactic fountain) acts on the mixing of interstellar matter ad energy over galactic scales. Matter going in and out of galaxies is though to be multi-phase, with a combination of cold and dense structures immersed in diffuse and hot gas. Among the topics we would like to explore is the state of the gas when it enters the disk, how the infall of matter trigger (or suppress) star formation, and how matter and energy are redistributed in the disk exactly.
The interstellar turbulence cascade is complex. It is magnetized and multi-phase, it is affected by stellar feedback, self-gravity and infall. Two major elements of the turbulent cascade are the energy injection and dissipation processes. These two bound the inertial range of turbulence, at large and small scales respectively. These processes define spatial and time scales that have important impacts on the way matter evolves and is organised. In particular turbulent energy dissipation might have an important non-linear effect on chemical abundances. Following on the work done at the previous Interstellar Institute sessions, discussion and work will continue to better understand this complexity, from the observational and numerical simulations point of views. In particular we will reflect on observational and numerical experiments that could be conducted in order to better understand and identify the main energetic processes and at which scales they occur.
The formation of stars occurs in gravitationnaly bound interstellar structures. The process by which interstellar matter condenses and fragments to reach that state is an essential element of the evolution of baryonic matter in galaxies. This process involves multi-phase and magnetized turbulence, cooling and self-gravity. Many questions are still unresolved. At which scales turbulence transits from subsonic to being dominated by shocks ? What is the relative importance of cooling, self-gravity and supersonic shocks in the structure formation process ? How is magnetic field impacting the structure formation process ? This sessions aims at studying this process in details, by combining numerical simulations, observations across the electro-magnetic spectrum and innovative data analysis techniques.