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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 358791.0, MPI für Astronomie / Publikationen_mpia
The calibration of mid-infrared star formation rate indicators
Authors:Calzetti, D.; Kennicutt, R. C.; Engelbracht, C. W.; Leitherer, C.; Draine, B. T.; Kewley, L.; Moustakas, J.; Sosey, M.; Dale, D. A.; Gordon, K. D.; Helou, G. X.; Hollenbach, D. J.; Armus, L.; Bendo, G.; Bot, C.; Buckalew, B.; Jarrett, T.; Li, A.; Meyer, M.; Murphy, E. J.; Prescott, M.; Regan, M. W.; Rieke, G. H.; Roussel, H.; Sheth, K.; Smith, J. D. T.; Thornley, M. D.; Walter, F.
Date of Publication (YYYY-MM-DD):2007
Title of Journal:The Astrophysical Journal
Start Page:870
End Page:895
Audience:Not Specified
Abstract / Description:With the goal of investigating the degree to which the mid-infrared emission traces the star formation rate (SFR), we analyze Spitzer 8 um and 24 um data of star-forming regions in a sample of 33 nearby galaxies with available HST/NICMOS images in the Paschen-alpha (1.8756 um) emission line. The galaxies are drawn from the Spitzer Infrared Nearby Galaxies Survey (SINGS) sample, and cover a range of morphologies and a factor ~10 in oxygen abundance. Published data on local low-metallicity starburst galaxies and Luminous Infrared Galaxies are also included in the analysis. Both the stellar-continuum-subtracted 8 um emission and the 24 um emission correlate with the extinction-corrected Pa-alpha line emission, although neither relationship is linear. Simple models of stellar populations and dust extinction and emission are able to reproduce the observed non-linear trend of the 24 um emission versus number of ionizing photons, including the modest deficiency of 24 um emission in the low metallicity regions, which results from a combination of decreasing dust opacity and dust temperature at low luminosities. Conversely, the trend of the 8 um emission as a function of the number of ionizing photons is not well reproduced by the same models. The 8 um emission is contributed, in larger measure than the 24 um emission, by dust heated by non-ionizing stellar populations, in agreement with previous findings. Two SFR calibrations, one using the 24 um emission and the other using a combination of the 24 um and H-alpha luminosities (Kennicutt et al. 2007), are presented. No calibration is presented for the 8 um emission, because of its significant dependence on both metallicity and environment. The calibrations presented here should be directly applicable to systems dominated by on-going star formation.
Free Keywords:Astrophysics
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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