A multiwavelength analysis of the clumpy FIR-bright sources in M33

• Published in: Monthly notices of the Royal Astronomical Society Vol. 441; no. 1; pp. 224 - 242
• Main Authors: Natale, G., Foyle, K., Wilson, C. D., Kuno, N.
• Format: Journal Article
• Language: English
• Published: London Oxford University Press 11-06-2014
• Subjects: Astrophysics; Dust; Luminosity; Morphology; Spectrum analysis; Star & galaxy formation; Temperature effects; H; galaxies: ISM infrared: galaxies; ISM: clouds; dust, extinction; regions
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stu560

We present a multiwavelength study of a sample of far-infrared (FIR) sources detected on the Herschel broad-band maps of the nearby galaxy M33. We perform source photometry on the FIR maps as well as mid-infrared (MIR), Hα, far-ultraviolet and integrated H i and CO line emission maps. By fitting MIR/FIR dust emission spectra, the source dust masses, temperatures and luminosities are inferred. The sources are classified based on their Hα morphology (sub-structured versus not-substructured) and on whether they have a significant CO detection (S/N > 3σ). We find that the sources have dust masses in the range 102–104 M⊙ and that they present significant differences in their inferred dust/star formation/gas parameters depending on their Hα morphology and CO detection classification. The results suggests differences in the evolutionary states or in the number of embedded H ii regions between the sub-samples. The source background-subtracted dust emission seems to be predominantly powered by local star formation, as indicated by a strong correlation between the dust luminosity and the dust-corrected Hα luminosity and the fact that the extrapolated young stellar luminosity is high enough to account for the observed dust emission. Finally, we do not find a strong correlation between the dust-corrected Hα luminosity and the dust mass of the sources, consistent with previous results on the breakdown of simple scaling relations at sub-kpc scales. However, the scatter in the relation is significantly reduced by correcting the Hα luminosity for the age of the young stellar populations in the star-forming regions.