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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 308633.0, MPI für Astronomie / Publikationen_mpia
The effect of star formation on the far-infrared-radio correlation within galaxies
Authors:Murphy, E. J.; Helou, G.; Braun, R.; Kenney, J. D. P.; Armus, L.; Calzetti, D.; Draine, B. T.; Kennicutt, R. C.; Roussel, H.; Walter, F.; Bendo, G. J.; Buckalew, B.; Dale, D. A.; Engelbracht, C. W.; Smith, J. D. T.; Thornley, M. D.
Date of Publication (YYYY-MM-DD):2006
Journal Abbrev.:The Astrophysical Journal
Start Page:L111
End Page:L115
Audience:Not Specified
Abstract / Description:Using data obtained for 12 galaxies as part of the Spitzer Infrared Nearby Galaxies Survey (SINGS) and the Westerbork Synthesis Radio Telescope (WSRT) SINGS radio continuum survey, we study how star formation activity affects the far-infrared-radio correlation within galaxies by testing a phenomenological model that describes the radio image as a smeared version of the far-infrared image. The physical basis of this description is that cosmic-ray (CR) electrons will diffuse measurably farther than the mean free path of dust-heating photons before decaying by synchrotron radiation. This description works well in general. Galaxies with higher infrared surface brightnesses have best-fit smoothing scale lengths of a few hundred parsecs, substantially shorter than those for lower surface brightness galaxies. We interpret this result to suggest that galaxies with higher disk-averaged star formation rates have had a recent episode of enhanced star formation and are characterized by a higher fraction of young CR electrons that have traveled only a few hundred parsecs from their acceleration sites in supernova remnants compared to galaxies with lower star formation activity.
Free Keywords:ISM: Cosmic Rays; Infrared: Galaxies; Radio Continuum: Galaxies
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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