LMC ⁺ : Large-scale mapping of [C II] and [O III] in the LMC molecular ridge

Context . The fundamental process of star formation in galaxies involves the intricate interplay between the fueling of star formation via molecular gas and the feedback from recently formed massive stars that can, in turn, hinder the conversion of gas into stars. This process, by which galaxies evolve, is also closely connected to the intrinsic properties of the interstellar medium (ISM), such as structure, density, pressure, and metallicity. Aims . To study the role that different molecular and atomic phases of the ISM play in star formation, and to characterize their physical conditions, we zoom into our nearest neighboring galaxy, the Large Magellanic Cloud (LMC; 50 kpc), the most convenient laboratory in which to study the effects of the lower metal abundance on the properties of the ISM. The LMC offers a view of the ISM and star formation conditions in a low-metallicity ( Z ~ 0.5 Z ⊙ ) environment similar, in that regard, to the epoch of the peak of star formation in the earlier Universe ( z ~ 1.5). Following up on studies carried out at galactic scales in low-Z galaxies, we present an unprecedentedly detailed analysis of well-known star-forming regions (SFRs) at a spatial resolution of a few parsecs. Methods . We mapped a 610 pc × 260 pc region in the LMC molecular ridge in [C II ] λ 158 µm and the [O III ] λ 88 µm using the FIFI-LS instrument on the SOFIA telescope. We compared the data with the distribution of the CO(2−1) emission from ALMA, the modeled total infrared luminosity, and the Spitzer /MIPS 24 µm continuum and H α . Results . We present new large maps of [C II ] and [O III ] and perform a first comparison with CO(2−1) line and L TIR emission. We also provide a detailed description of the observing strategy with SOFIA /FIFI-LS and the data reduction process. Conclusions . We find that [C II ] and [O III ] emission is associated with the SFRs in the molecular ridge, but also extends throughout the mapped region, and is not obviously associated with ongoing star formation. The CO emission is clumpier than the [C II ] emission and we find plentiful [C II ] present where there is little CO emission, possibly holding important implications for “CO-dark” gas. We find a clear trend of the L [C II ] /L TIR ratio decreasing with increasing L TIR in the full range. This suggests a strong link between the “[C II ]-deficit” and the local physical conditions instead of global properties.