Suzanne Madden
AIM, CEA, Saclay
Investigating low metallicity PDRs and molecular clouds: Insights from the SOFIA Legacy program, LMC+
The intricate interplay between the fueling of star formation via molecular gas and feedback from massive stars is closely linked to the local and global properties of the interstellar medium (ISM) of galaxies, such as metallicity, structure, density, pressure, metallicity, etc.. The mass of H2, normally traced by its convenient, observable proxy, the CO molecule, serves as an indicator of star formation activity for both nearby and high-redshift galaxies. However, studies of local universe low-metallicity star forming dwarf galaxies reveal a puzzling discrepancy between the apparent meager molecular gas inferred from CO observations and the notably high star formation activity, posing a challenge to accurately determine the conversion of CO to the total H2 gas mass in low-metallicity environments. This hampers our ability to fully grasp and accurately simulate the evolution of molecular clouds leading to star formation in metal-poor, early universe galaxies, where our local dwarf galaxies may serve as valuable benchmarks. Our investigation of unresolved local universe dwarf galaxies highlights the prominent far-infrared [CII] as a potential tracer of the total molecular gas reservoir in low-metallicity environments. To get a better handle on the assessment of the molecular gas in low-metallicity environments, we zoom into our nearest low metallicity galaxy, The Large Magellanic Cloud (LMC), through the SOFIA Legacy Program, LMC+, which has mapped the molecular ridge south of 30Doradus in the 158 mu [CII] and the 88 mu [OIII] lines. By comparing the LMC+ observations to the ALMA CO from this region we aim to understand the local conditions that govern the presence CO-bright vs. CO-dark regions and how this relates to star formation. Wide variations in the observed [CII]/CO ratio, for example, reveal the complexity of the properties of the PDRs, molecular clouds and star formation processes. This study holds implications for understanding the process of star formation in early universe galaxies where ALMA observations of [OIII] and [CII] are emerging.
