Dissecting the Mid-infrared Heart of M83 with JWST

Molecular gas is a critical ingredient in the recipe of star formation (SF) in galaxies. To fully understand the processes that govern SF, it is essential to accurately measure and characterize the distribution of H2 in star-forming environments. Since H2 is a weak rotational emitter, the molecular gas content in galaxies is typically inferred using indirect tracers such as the CO (1-0) transition. However, CO provides a partial census of the total H2 mass, particularly in regions with large quantities of CO-dark gas. A few years ago, an HST/FUV spectroscopic study proposed that the starburst region in the nearby galaxy, M83, would be an ideal environment to host CO-dark gas. We have begun exploiting the unprecedented capabilities of JWST in the MIR, using the MIRI/MRS, performing a study of the warm H2 gas in the heart of this face-on spiral galaxy. Our initial results indicate that a large fraction of the total molecular gas mass in the core of M83 is contained in the warm H2 component, hidden to the CO tracer. We are now performing a more in-depth, detailed analysis probing the distribution of this gas on spatial scales ~5 pc, uncovering the effect recently-formed massive stars, observed with HST/COS, have on the reservoirs of molecular gas and star formation. It is imperative that we understand the fueling star-formation history through cosmic time, and the unmatched synergy of HST and JWST is allowing us to do exactly that.