Disentangling emission from star-forming regions in the Magellanic Clouds: Linking [O iii]lambda 88 mu m and 24 mu m

Context. The [O iii]lambda 88 mu m line is observed in many galaxies including our neighboring Magellanic Clouds and is a well-known tracer of H ii regions, while the 24 mu m continuum emission has often been used to trace warm dust in the ionized phases of galaxies. The association of both the [O iii]lambda 88 mu m line and 24 mu m in galaxies to star formation motivates this study to determine their observational relation. Aims. This study explores the link between the [O iii]lambda 88 mu m and 24 mu m continuum in star-forming regions in the Magellanic Clouds. We also explore the local conditions driving the relation between those tracers. Methods. We compared observations with 1D Cloudy models consisting of an H ii region plus a photodissociation region (PDR) component, varying the stellar age, the initial density (at the illuminated edge of the cloud), and the ionization parameter. We introduced a new parameter, c(PDR), to quantify the proportion of emission arising from PDRs and that with an origin in H ii regions along each line of sight. We used the ratio ([C ii]+[O i])/[O iii] as a proxy for the ratio of PDR versus H ii region emission, and compared it to the [O iii]/24 mu m ratio. The use of [O iii]/24 mu m and [O iii]/70 mu m together allowed us to constrain the models most efficiently. Results. We find a correlation over at least 3 orders of magnitude in [O iii]lambda 88 mu m and 24 mu m continuum. This correlation is seen for spatially resolved maps of the Magellanic Cloud regions as well as unresolved galaxy-wide low metallicity galaxies of the Dwarf Galaxy Survey. We also find that most of the regions have low proportions of PDRs along the lines of sight (<12%), while a limited area of some of the mapped regions can reach 30-50%. For most lines of sight within the star-forming regions we have studied in the Magellanic Clouds, H ii regions are the dominant phase. Conclusions. We propose the use of the correlation between the [O iii]lambda 88 mu m and 24 mu m continuum as a new predictive tool to estimate, for example, the [O iii]lambda 88 mu m when the 24 mu m continuum is available or inversely. This can be especially useful to prepare for Atacama Large Milimeter Array (ALMA) observations of [O iii]lambda 88 mu m in high-z galaxies. The simple and novel method we developed may also provides a way to disentangle different phases along the line of sight, when other 3D information is not available.