Herschel photometric observations of the nearby low metallicity irregular galaxy NGC 6822

Galametz, M.; Madden, S. C.; Galliano, F.; Hony, S.; Sauvage, M.; Pohlen, M.; Bendo, G. J.; Auld, R.; Baes, M.; Barlow, M. J.; Bock, J. J.; Boselli, A.; Bradford, M.; Buat, V.; Castro-Rodríguez, N.; Chanial, P.; Charlot, S.; Ciesla, L.; Clements, D. L.; Cooray, A.; Cormier, D.; Cortese, L.; Davies, J. I.; Dwek, E.; Eales, S. A.; Elbaz, D.; Gear, W. K.; Glenn, J.; Gomez, H. L.; Griffin, M.; Isaak, K. G.; Levenson, L. R.; Lu, N.; O'Halloran, B.; Okumura, K.; Oliver, S.; Page, M. J.; Panuzzo, P.; Papageorgiou, A.; Parkin, T. J.; Pérez-Fournon, I.; Rangwala, N.; Rigby, E. E.; Roussel, H.; Rykala, A.; Sacchi, N.; Schulz, B.; Schirm, M. R. P.; Smith, M. W. L.; Spinoglio, L.; Stevens, J. A.; Sundar, S.; Symeonidis, M.; Trichas, M.; Vaccari, M.; Vigroux, L.; Wilson, C. D.; Wozniak, H.; Wright, G. S.; Zeilinger, W. W.
Bibliographical reference

Astronomy and Astrophysics, Volume 518, id.L55

Advertised on:
7
2010
Number of authors
60
IAC number of authors
2
Citations
51
Refereed citations
45
Description
We present the first Herschel PACS and SPIRE images of the low-metallicity galaxy NGC 6822 observed from 70 to 500 μm and clearly resolve the H ii regions with PACS and SPIRE. We find that the ratio 250/500 is dependent on the 24 μm surface brightness in NGC 6822, which would locally link the heating processes of the coldest phases of dust in the ISM to the star formation activity. We model the SEDs of some regions H ii regions and less active regions across the galaxy and find that the SEDs of H ii regions show warmer ranges of dust temperatures. We derive very high dust masses when graphite is used in our model to describe carbon dust. Using amorphous carbon, instead, requires less dust mass to account for submm emission due to its lower emissivity properties. This indicates that SED models including Herschel constraints may require different dust properties than commonly used. The global G/D of NGC 6822 is finally estimated to be 186, using amorphous carbon. Herschel is an ESA space observatory with science instruments provided by Principal Investigator consortia. It is open for proposals for observing time from the worldwide astronomical community.Figure 5 is only available in electronic form at http://www.aanda.org.
Related projects
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Formation and Evolution of Galaxies: Observations in Infrared and other Wavelengths
This IAC research group carries out several extragalactic projects in different spectral ranges, using space as well as ground-based telescopes, to study the cosmological evolution of galaxies and the origin of nuclear activity in active galaxies. The group is a member of the international consortium which built the SPIRE instrument for the
Ismael
Pérez Fournon